Radio Frequency Generator? Answered

Hi I am doing a project and it requires a radio (or anything longer than human eyesight) frequency generator. Is there any easy way i can do this, with parts from home or radioshack?

Question by LiquidLightning   |  last reply



Radio frequency program for computer

I am trying to modify an old am fm radio, so that it can pick up transmissions from a walkie talkie. I know the frequency at which the walkie talkie operates, but I can not tell the frequency of the radio when I am adjusting it. Is there any computer program, or something that can tell me what frequency I have?

Topic by Sedgewick17 


Bluetooth vs Radio Frequency Answered

This is a 3 part question: 1. I am a bit confused. Radio frequency covers 3KHz to 300GHz, so it basically includes bluetooth(2.4 GHz). Why is it that some people talk about bluetooth as something not relating to RF. Do they have different transmission methods? WIFI is also @ 2.4GHZ. What is the distinction between WIFI and bluetooth that makes them so different, covering different ranges, and being able to send different amounts of data at different speeds. I always thought it was the frequency of the wave but WIFI and bluetooth are the same yet they are so different.  2. I am building a project. I need to send data wirelessly. The data is very simple just to turn on or off a series of leds. A friend of mine told me to use radio waves. What does he mean by that exactly since radio range is huge. Is he talking about 40MHz like the RC cars? 3.Bluetooth or RF(again im assuming this to be the same one as RC cars since i will break apart an RC car to remove the transmitter/receiver)Which method consumes less power to send the same amount of data. Distance will not be over 10 meters so i'm not worried about that.  Thanks for the help everyone, much appreciated! Chris

Question by Chris414   |  last reply


Radio Frequency Proximity Detector

Hello, Does anyone have an instructable for building a proximity detector based on a radio transmitter and receiver? Or some other wave based method? I've viewed the IR proximity detector here on this site, but I need a transmitter/receiver based one. Yes, this is for my pet. I have 2 cats and 1 dog. I need to keep the dog out of the same areas that the cats are allowed to go into, thus the proximity detector needs to be specifically tuned to the dog. Distance does not have to be far, anywhere from several inches to a couple feet. Appreciate any comments or instructables! Thanks, Eric

Topic by riccarr   |  last reply


Using 433M-Transceiver-Module-E32-TTL-1W-SX1278-SX1276-30dBm-LoRa-Long-Range-433MHz

How do i use  433M-Transceiver-Module-E32-TTL-1W-SX1278-SX1276-30dBm-LoRa-Long-Range-433MHz with arduino uno, like schematics, codes, what is MO, M1 to transfer data as I can not find much about it. Cheers

Topic by laidlow7 


Arduino + RF to create item/finder?

IDEA 1. I've got the idea to create this kind of project where people nowadays being careless and misplace their item. So to counter this problem, i want to create a device which can detect the object/item within an area/radius of the receiver and transmitter. 2. This is not only for item/object but also can be placed on your children just in case they are away from you thus this device can alert you in sound, sight ( blinking LED ) , and vibration. PROBLEM 1. Is it possible to only use 1 transmitter and receiver? 2. Just in case for future uses, can compass be implanted in this device where it will always shows to the transmitter? 3. Currently programming are very hard for me, where can i get reference for programming this kind of device?

Question by Isaace11   |  last reply


Sattelite radio

I have a satellite radio. Got it from World space satellite radio inc. Since it got bankrupt in India , i cant avail any service. 1.Can i reuse it by subscribing to other company 2.Can i use it for some other technology eg. use it as local receiver. say something compatible with the frequencies that satellite radio use.

Topic by jagmeetsinghsaluja   |  last reply


Radio Mod?

I would like to mod a handheld radio (or even a analogue tv but radio would be better) to get to listen to higher frequencies than normally available. I'd Like to hit the 1420Mhz mark approximately but with little electrical engineering or architecture experience, I'm not certain how? Which might make a TV easier to get there as UHF covers that right? (still safer to play with a battery powered radio than a 240V powered one) I figured there is someone out there with the ability to figure out what components need changing? The variable resistor that tunes it perhaps? If you'd rather post an instructable I'll follow that or just tell me what needs replacing with what? Any Ideas?? Thanks

Question by Mr E Man   |  last reply


Nanotube Radio

Nanotube Radio: Supplementary materialsK. Jensen, J. Weldon, H. Garcia, and A. ZettlDepartment of Physics, University of California at BerkeleyCenter of Integrated Nanomechanical Systems, University of California at BerkeleyMaterials Sciences Division, Lawrence Berkeley National LaboratoryBerkeley, CA 94720, U.S.A.We have constructed a fully functional, fully integrated radio receiver, orders-of-magnitude smaller than any previous radio, from a single carbon nanotube. The single nanotube serves, at once, as all major components of a radio: antenna, tuner, amplifier, and demodulator. Moreover, the antenna and tuner are implemented in a radically different manner than traditional radios, receiving signals via high frequency mechanical vibrations of the nanotube rather than through traditional electrical means. We have already used the nanotube radio to receive and play music from FM radio transmissions such as Layla by Eric Clapton (Derek and the Dominos) and the Beach Boy's Good Vibrations. The nanotube radio's extremely small size could enable radical new applications such as radio controlled devices small enough to exist in the human bloodstream, or simply smaller, cheaper, and more efficient wireless devices such as cellular phones....This is the site of the original article

Topic by Goodhart   |  last reply


How do I attach a frequency counter to a Uniden 2020 Amature Radio?

We have a Uniden 2020 Amature Radio. We also have a Frequency counter. Wondering if anyone has connected the two together so that frequency can be read off the frequency counter.

Question by emit 


High Frequency Alternators

Look at a picture of some arcs from a common spark-gap Tesla Coil, and then compare it to the arcs from a solid-state. What makes the two so different? The difference comes from the Solid-State Tesla Coil to operate in CW (constant wave) mode. This means that its power supply is uninterrupted, whereas in a spark-gap type, power is being switched on and off hundreds of times per second. If the output terminal of a CW coil doesn't have a brake out point, no corona or spark will occur. For anyone who's investigating wireless power transmission or Tesla's version of radio, this is a very helpful feature, since corona only wastes energy. And if it does have a brake out point, it can create some pretty interesting spark displays, as I mentioned above. An arc to a grounded object increases the current in the arc to such a point that it turns into a white-hot "flaming" discharge. All-in-all, a CW type coil is a pretty interesting kind to observe. But solid-states can be pretty difficult and annoying to build, and expensive as well. Since solid-state technology obviously was not available to Tesla, he found a different way to operate his coils in CW mode- a generator that was specially designed to produce radio-frequency power. He had originally created it for high-frequency arc lighting. Today, I have seen absolutely no coils run by a high frequency alternator. Of course, an alternator would be admittedly difficult to build, but since it could probably deliver more power than a solid-state coil, it would be worth it. Does anyone know if there are any companies that still make these alternators? Would anyone be interested in recreating it? Should we even bother? Thank you for listening. Peace!

Topic by ElectricUmbrella   |  last reply


Radio control question Answered

Would putting a 27 mhz frequency crystal  instead of the one shown, and a ajusting it to the right amplitude make a RC work  with this curcuit http://sci-toys.com/scitoys/scitoys/radio/am_transmitter.html?

Question by jbaker22   |  last reply


What radio frequencies will be legal for wireless microphone use in 2012? Answered

Hello, I will be wanting to purchase UHF microphones that comply with the new frequency changes in the UK. I have found many recourses on the internet but none seem to match up? I would be very grateful if someone were to tell me what channels you can operate on (license exept) in 2012. Many Thanks Oscar

Question by oscarthompson   |  last reply


How to make a single frequency am radio receiver?

I know how to make a 1 mhz am radio transmitter, so now I want to make a 1 mhz radio receiver to receive audio. I would prefer to not have to wind any coils and just make solid state with few components. Do I need to have a coil to receive the radio waves? Also can someone link me to an explanation or explain how I can demodulate with a 1 mhz crystal oscillator. I don't want a link to 'how to make an am radio' I can do that myself. I just want to know A. how to receive the radio signals hopefully without a coil (only using a variable cap?) and B. How I can demodulate using a crystal oscillator. Can I somehow receive the signal using an oscillator like was done with a 555 timer here https://www.instructables.com/id/555-timer-radio/ Links to schematics / pictures of schematics must appreciated? Thank you

Question by sk8aseth   |  last reply


FM Transmitter mod help

Does anybody have any idea how to modify a car FM transmitter for an mp3 player so that it will transmit in frequencies other than the low and high extremes built into it? Also would it somehow be possible to make it transmit to all FM frequencies at the same time? If someone could help me out with this I would really appreciate it.

Topic by kurdiz   |  last reply


Antenna length for a frequency modulated signal.

I  am given to understand that the length of an antenna is proportional to the wavelength of the signal that is fed to it (a quarter wavelength, for example). In the case of a signal modulated by amplitude, the frequency (and therefore wavelength) of the carrier wave remains unchanged. However, in the case of a signal modulated by frequency, the signal fed to the antenna will vary in frequency (and, therefore, wavelength). My query is this : how would one go about calculating the length of an antenna for a frequency modulated signal? Its frequency is not constant, so to construct an antenna of say, a quarter of the wavelength, would be impossible. I thank you in advance for your assistance. AlexHalford

Question by alexhalford   |  last reply



Request: Sound canceller / radio frequency canceller

Request: Sound canceller / radio frequency canceller. Here's the sound canceller, which is prices at around $30,000 Euros, and powers itself. (using radio frequency) http://www.digitaltrends.com/wp-content/uploads/2013/10/sono-technical-setup.jpeg Aditional request:  Radio Frequency canceller.  Ideally it would be something similar in concept, but would be able to cancel specific ranges also. Thanks.

Topic by WyattsAccount   |  last reply



Can you piggyback RF communications on cellular transmit/receive frequency bands ?

My question is purely hypothetical and there is no immediate plans for any such application. But I was just curious is it possible to make use of the cellular frequency bands (as set out by a country's regulations and by the cellular providers) for some sort of covert type communication other than for voice, data or text types of cellular communications ? Would it be too difficult and complex to develop such an application that uses cellular radio frequencies or could it be done without too much concern for potential interference or the sharing of channels of nearby normal cellular transmissions ? Could such an application be developed without having to cross over many hurdles ? If this covert communications is possible would the cell frequencies used not reach the base stations of the wireless carriers as noise or can a peer to peer communications be possible by passing the base stations ?

Topic by victor43   |  last reply


I need to repeat radio frequency in the 402MHz range.

I need to repeat radio frequency in the 402MHz range.  How do you build a RF repeater? I need to extend the range of a CGM (Continuous Glucose Monitor). It uses the MICS protocol.  Can you adapt an existing device?

Topic by arourke1   |  last reply


How do you determine the length of an antenna and the size of a fractal antenna? Answered

In an instructable, the formula for calculating antenna length was given as "length in meters =300 / frequency in MHz".  The example given was for a Bluetooth antenna with a frequency of 2450MHz.  The antenna length was calculated as 300/2450 = 0.1225m = 12cm.  The author then divided it by 4 to make a "quarter wave" antenna length of 30mm.  Why divide it by 4 and what is the benefit of a "quarter wave" antenna.  What is the effect of the conductor leading to the antenna?  If the 30mm antenna is soldered to a 4mm lead, does that result in a 34mm antenna?  For a fractal antenna, should the 30mm length of wire be folded into a fractal shape or should the total fractal antenna be 30mm in width?  I have read somewhere that one of the benefits of a fractal antenna is that they are able to receive signals of different wave lengths.

Question by fcampbell   |  last reply


I need a small FM radio tuner that can be set up for presets?

I need a small form factor FM frequency radio with tuner that can be set up for presets and to a plug in power supply To be used on a exercise machine. It also needs a headphone jack.

Question by fiteqprpr 


RF Radio Frequency Amplification RC Car with HMC478MP86E

I found rf amplifier up to 4.0ghz,it called HMC478MP86E right? My rc car use 2.4 ghz tx signal,on the datasheet,2.0 - 3.0 ghz the output is 16 dBm,the seller told me parallel it to make the output signal stronger. The question is what the dBm output after parallel? is it 32 dBm? its 1.4 W wow :D,is it right? sorry for my bad english :D fyi,im make fpv car so i can play it from house with the camera

Question by mismail15   |  last reply


minature camera with radio signal?

I am in Model Railroad.  I have purchased a commercial camera kit where I mount the camera in a train engine, send it down the track and the image is sent to my tv.  It has not worked to satisfactorly and I'm wondering if anyone has come up with a DIY version. Thanks.   HLM.

Question by HarrisCreekCentral   |  last reply


Audio Detector

Is there some type of electrical component which detects high frequency sounds like those mosquito ring tones? I've looked around and seen things which apparently detect high frequency radio waves, but that isn't really what I want (at least I don't think it is). Thanks in advance.

Topic by brickzima   |  last reply


is it possible to make video come through as a radio frequencey?

I was wondering if anyone has managed to figure out how to send video through a radio frequency? i need for an rc project to make a video signal come through a radio frequency, then onto a pc/laptop and can be viewed in / as close to real time as possible.  

Question by duelist   |  last reply


What frequency are aircrafts flying out of gatwick and could these listen to it ?

Http://cgi.ebay.co.uk/Omega-Multi-Band-Radio-Scanner-Icon-3-Air-Band-Marine-/120600101374?cmd=ViewItem&pt;=UK_ConsumerElectronics_SpecialistRadioEquipment_SM&hash;=item1c145381fe#ht_500wt_1154

Question by wizzywoo   |  last reply


what are the problems i can face in this project? Answered

My goal is transmit square wave with certain frequency from fm transmitter and receive this square wave by fm receiver on the other side in order to be measured by pic microcontroller and the range between TX and RX is 100m or 120m max  i want it to be as simple as i can so i made a research and my plan is : 1) square wave generator using 555 IC so i can control the frequency and amplitude the circuit is in the following link: http://www.learningaboutelectronics.com/Articles/Adjustable-square-wave-generator-circuit-with-a-555-timer.php 2) the output of square wave generator i will use it as input for Fm transmitter the circuit is in the following link :https://www.instructables.com/id/The-Ultimate-FM-Transmitter/ 3) i will use small radio i have to receive the square wave on radio speaker the sound should be like the following link : http://onlinetonegenerator.com/ to be sure that my square wave has reached the speaker  4) then i will hack the radio :) and remove the speaker and use the radio output as input for pic microcontroller to measure the square wave frequency   so eventually the stages will be like this: sinwave genetrator > FM transmitter > FM receiver > microcontroller used to measure frequency and display it on LCD screen  i made fm transmitter before and received sin wave tone by fm radio so i expect the problem will be in using FM receiver as input to microcontroller to measure frequency  what do you think about this plan ?? 

Question by ShadyM1   |  last reply


trying to build a wireless alarm system off a motion detector. How do I alert the mobile remote, radio frequency?

How do i builder a radio frequency to alert my wireless remote that the motion sensor has gone off? can someone please explain the whole frequency to me?? very urgent would really appreciate the help! thanks for your time over looking my problem.

Question by darrenlefever   |  last reply


Does anyone know how to make a radio constantly scan? Answered

I want to take an ordinary FM radio and make the scan function cycle through all of the frequencies very quickly and constantly. Any advice?

Question by transistorguy   |  last reply


Where can I get a powerful 14 MHz radio wave generator, and what can contain the waves? Answered

I need a somewhat powerful 14 MHZ radio wave generator. I know that these frequencies are probably illegal, so what can best contain them? I have heard that Faraday Cages can, and a parabolic reflector has also ocurred to me. What would be best to contain them, and is it possible to build one?

Question by Technicolor   |  last reply


can I reprogram the radios in my cell phone for other uses like walkie talkie or shortwave CB Ham reciever?

Cell phones have radio receivers and transmitters ;  it can receive FM radio, transience Blue tooth, WIFI, and Cell phone radio several bands and frequencies.      It seems to me that those chips could be programmed for other frequencies for transmitting and receiving.  I haven't researched into how flexible these chips are and if they can be reprogrammed in the smart phone.  Maybe someone else has.

Question by Rayhowes   |  last reply


converting bluetooth message to rf 433mhz?

Can Arduino convert the incoming message from bluetooth frequency to Rf 433Mhz and then retransmit it at this frequency? if yes then are all arduino shields capable of doing this? 

Question by christian.badua3   |  last reply


What can I use to shield cellphone radio waves/ frequencies? Answered

I always put my cellphone in my right pocket, only the right pocket, keys and wallet go on the left. I noticed awhile back that my leg sometimes twitches. So now I was wondering if I can line my pocket with something that will shield the radio waves from my leg. What would work?

Question by Koosie   |  last reply


Can I use a 555 timer IC to make an amateur radio?

                    I'm thinking about starting to do amateur radio, but I don't want to pay a ton of money for a transceiver.  In theory, couldn't I use a 555 timer with a frequency modulated by a microphone to generate FM, which could then be amplified and transmitted?  Just curious about it.  Also, couldn't one do the same thing in reverse, just finding a way to tune a 555 or something so that it would output audio when tuned to a specific frequency from an antenna?  Just a thought. 

Question by mad magoo   |  last reply


Are rc airplanes allowed to operate on rc car frequencies?

I know that rc cars are not allowed to operate on rc planes frequencies, but what about vice versa?

Question by tesla man   |  last reply


EMP generator

Back in the late 50's the Heathkit company had a "build-it-yourself" radio kit based on the early TRF (tuned radio frequency) radio. For you younger guys, these radios were not superhetrodyne like our modern radios where one only has to rotate a single knob to change stations. With the TRF one had to tune each stage of amplification to the frequency of the desired radio station. At any rate, I bought one of these kits when I was in the Air Force and found, quite by accident, that if I tuned to a radio station that one of my buddies was listening to in the barracks, and then detuned slightly, I could jam his radio. Drove him nuts! But the best part came later when, on one weekend I looked out of the barracks window and, lo and behold! there was a guy washing his car while listening to his radio. Ha! So, I got out my trusty TRF, found the frequency the car radio was tuned to - AND JAMMED IT! Today, that guy is still wondering what the hell was wrong with that radio. I never tested at what range I could jam radio channels, but the car was a good 100 feet away. Now, this device will work with AM radios but not with FM, unfortunately (not without a lot of modification of the TRF).

Topic by jjg3 


Simple AM transmitter

I wish to make an extremely small (size and part count) AM transmitter using only a few transistors and passive components. I wish to transmit an audible tone on a set frequency.I am thinking along the lines of a transistor flip-flop circuit oscillator, perhaps routed through another. It really needs to have less that five/six small components. DIP components are too big. Small electrolytic and other capacitors, transistors, and resistors are acceptable. Transmission distance needs to be at least 1/4 of a meter, but further is better. It needs to run on between 1.5 and 6 volts, low to middle'in milli-ampage im thinking watch batteries for a few hours at least. I have read the following article but as stated before it needs to be very small. https://www.instructables.com/id/Make-a-simple-AM-transmitter/Can anyone help me out with a schematic, thoughts or advice?Thanks in advance,-AndyP.s. I can work out transistor loop timings and I understand how the Amplitude Modulation system works. Current thoughts/plans (if you can call them that) are an audible tone switching a secondary transistor loop from high (no resistor in series) to low (resistor in series) power and back. The secondry loop will be switching at the target frequency.

Topic by andy   |  last reply


What is the highest legal power for an FM radio wave generator in the United States? Answered

I am building a project that transmits FM radio waves about a mile with frequencies capable of being picked up by a normal FM radio. I know that those little iTrip connectors for the iPod can legally generate FM signals capable of being picked up by a car's radio antenna, but a mile of transmission seems a bit excessive to me. Would such a device be illegal? Does anyone have any links where I can find such information? Thank you.

Question by Technicolor   |  last reply


long range radio control flying

Hello all...I was looking in at the discussions of the possibility of long range radio control airplane operation and can make a few comments drawn from my research into the topic, with my opinions directed toward the USA market area ; First, Americans are bound by Federal Communications Commission regulations so we must abide by them or risk steep fines or legal trouble if caught. Second, the frequencies assigned by the FCC for radio control hobby use are already allocated, so modifications to your control systems in terms of frequencies could be illegal. Third, the maximum output for radio systems in the hobby is 1000mw (1 watt), which will easily control your miniature aircraft out to 1 to 2 miles, where you will need a video camera, transmitter, reciever and viewing device to even keep track of it ! There are several manufacturers that are way ahead of most of us here - offering pre made systems that are plug and play (no head scratching needed) . Search "FPV systems" on your computer and you'll find them. Bear in mind that to use these systems in America, you will need to obtain an amateur radio (ham) operator license to be legal (again, so if you get checked, you won't get in big trouble with the Federal Government ). I'm still looking into it myself, but if you want to see a good example of a really sharp Canadian who has a handle on this, search " VRflyer" on YouTube. He started doing this quite a few years ago and has some great video of his projects and results !

Topic by 2512rc 


Crystal radio help anyone?

(If you want the blow-by-blow of my questions, skip the following gigantic piece of text and proceed to the 2nd list after the first)   I was reconsidering making a crystal radio the past week and so I set out to research the topic on the 2nd most popular information database on the internet which comes out of the 1st most popular one. According to wikipedia, all you need is one diode in order to split the AC signal coming in via the antenna in half, therefore it uses half-wave rectification (it's not quoted; it's what I understand from it). Could full-wave rectification be also used? Like connecting the antenna to a bridge rectifier (aka. diode bridge, aka. 4 diodes stuck together)? I know that half-wave rectification yields pulsed DC, but I also don't understand how. By that I mean what happens to the other half? Does the other half of the wave connect directly to the output? One last thing, I know the largest metallic object I can ever use as an antenna is basically just my roof, but then I don't like coming up to the roof and looking for some exposed metal to connect to. Any thoughts on what huge, metallic items I can use in my household? I've already thought up a list of what I could use for an antenna: -Window screens -Extremely long piece of wire (I have an 8 meter long CAT5 cable going from the 1st to the 2nd floor) -My front gate -Sheet metal laying outside my front door (not the gate) Here is the summary of all my questions: -Is this wikipedia article true? (see at the list "semiconductor" area) -Can full-wave rectification be used on such radios? -In the case of half-wave rectification, where does the other half of the signal go? -What can I use as an antenna (excluding my roof)? Aside from the asked questions: -Is there any other way to tune to a particular frequency? -I'm asking opinions to people who know what they're doing (no offense to beehard44, this is more of a poll that anything else).

Question by nutsandbolts_64   |  last reply


Short range radio pulse transmitter design?

I need something simple to transmit pulses 2-3 meters to a receiver The transmitter will output a pulse every few seconds, transmit a small burst at X frequency. The receiver then outputs a short high pulse/outputs high for the duration of the received pulse. I want this to be as simple as it can possibly be, cost being the primary restriction and power usage being also of fairly high importance, so please no suggestions of Bluetooth or xbee type systems. It does not have to be a radio based system, however it needs to work without line of sight and of course without connecting wires. If it helps the overall aim is a 'safety signal' that will set of an alarm at the receiving end if several pulses are missed Anyone? EDIT: To clarify I am looking for simple, like really simple. So the transmitter is just a resonator and antenna. What I need is a simple receiver that will respond to a specific frequency, on or off. Does such a thing exist? 

Question by Damp Cuttlefish   |  last reply


Why to use RF directional couplers in some measurements and control processes ?

I am an electronic engineer in the field of RF directional couplers, but I am puzzled about this question, why to use RF directional couplers in some measurements and control processes ? Today I come to this forum to turn to you to discuss my understandings are appropriate. Here are my personal understandings: RF radio frequency is referred to as RF current, it is a high frequency AC change electromagnetic wave short. Less than 1000 times per second changes in alternating current called low frequency current, more than 10000 times called high frequency current, and radio frequency is such a high frequency current. RF technology in the field of wireless communications with a wide range of irreplaceable role. In the electronics theory, the current flows through the conductor, the conductor will form a magnetic field around; alternating current through the conductor, the conductor will form an alternating electromagnetic field, known as electromagnetic waves. When the electromagnetic wave frequency is lower than 100khz, the electromagnetic wave will be absorbed by the surface, can not form an effective transmission, but the electromagnetic wave frequency is higher than 100khz, the electromagnetic wave can be spread in the air, and the outer edge of the ionospheric reflection, the formation of long-distance transmission capacity (Analog or digital) with high-frequency current modulation (amplitude modulation or FM), the formation of radio frequency signals, through the antenna to launch into the air, the radio frequency of the high-frequency electromagnetic waves.  Long-range radio frequency signal received after the anti-modulation, reduced to the electrical information source, this process is called wireless transmission. Wireless transmission developed for nearly two hundred years, forming a large number of users and product groups, but because of climate change and the impact of surface obstacles, can not transmit the perfect information. Modern human invention of the cheap high-frequency transmission cable (radio frequency line), in order to pursue the perfect quality of information transmission, taking into account the original wireless devices, wireless cable transmission began to pop. Resulting in the concept of radio frequency transmission. If your information source through the secondary modulation, with the cable to the opposite end, the opposite side with anti-modulation of the information source after the re-application, no matter how low frequency, but also radio frequency transmission, if there is no modulation anti-modulation process, The information source is transmitted directly to the opposite end of the cable, no matter how high the frequency, are the general cable transmission. SI --- Signal Integrity Signal Integrity PI --- Power Integrity Power Integrity emc --- electromagnetic compatibility Electromagnetic Compatibility rf - radio frequency RF emc = emi + ems EMI = Conduction + Radiation Emission SI: The Fourier transform shows that the higher the signal rises, the higher the amplitude of the higher harmonics. The MAXWELL equations see that these alternating harmonics produce alternating current at the adjacent line. And even through the space parasitic capacitance directly to another conductor, so these high harmonics is caused by radiation interference (emission) of the main factors; (that the simple point is that the signal rise faster, the more complete the signal, the better the signal quality, But for emi bad) . PI: PCB exists on the number \ \ analog area, high frequency \ 'low frequency region and other different areas and planes, if the partition is not easy to interfere with each other, that is, conduction conduction (conduction). Ps: Excuse me if I was wrong in words or expressions as I am a green hand in the field of RF directional couplers. I need continual learnings. What is your idea ? Do you agree with my ideas ? Any of your ideas would be highly appreciated. May someone would like to help ? thanks in advance.

Topic by maryzhu   |  last reply


FM Transmitter: Please help decode diagram/power properly (Mandarin or Catonese would be helpful)

I just need to figure out how to power this thing! Notice the positive marks in both upper corners, the negative in both lower? The large circle is the microphone, which is fully wired. The smaller circle is the frequency modulation, which is all set as well. The underside only has holes where the gray squares are and is otherwise clean (exception being one spot where the two mounting prongs of the microphone pushed through.) Thanks

Topic by owhy   |  last reply


Air Traffic Control on PC

Air Traffic control broadcasts from 108 - 138 MHz. (https://www.instructables.com/id/Transistor-Radio-Hack/)A couple of months ago I bought a Realistic Jetstream radio. It was used. I saw it there before. I finally bought it. I thought it was just an FM/AM radio. It said AM/VHF. I thought that was odd. After I bought it I realized that it wasn't an FM radio, it was an Air Traffic Control scanner! That was even better. It comes apart just like the radio Kipkay used in the hack. It was already an ATC radio though. My question is there any way to get Air Traffic Control on your computer? I tried an old tv tuner card. I set the frequency to 122.8MHz. That is the frequency for the local airport in Microsoft Flight Simulator 2004: A Centruy of Flight. It is also what my radio picks up. The antenna won't pick it up on the tuner. FM radio works though. I hope all this makes sense.

Topic by popit   |  last reply


SDR - Software Defined Radio, are you hooked?

Using a cheap USB dongle and an antenna everyone can listen to broadcasts.This includes HAM radio, VHF, UHF, DAB, data servives, satellite communications and even the ISS.Pagers can be listed too if you still find someone using them but getting the latest weather might be nice as well.What are you listening to, what data do you decode?What is you best story in regards to your SDR experience?Prefered programs?

Question by Downunder35m 


How can I replace a single wire with an infrared link?

I just want to have a digital communication interface become infrared. I have data going both directions, so I need to have the system be two-way. If possible, I would prefer using radio of some sort. For infrared, would it be as simple as an IR LED and NPN phototransistor at each end? EDIT: Bad news. The system needs 2 wires to transfer data. Since IR would mix together, I need to use 2 different radio frequencies. Does anyone know how to send and receive simple pulses of radio waves?

Question by 4lifenerdfighter   |  last reply


How do i calculate the size of a dish i need for a specif frequency, specifically around 95 mhz?

How do i do so? I plan on making a home made radio telescope, but i just want to block out non-space made noise.

Question by natman3400   |  last reply