All Questions

Recently, ultra-wideband technology has been in the news again. From the Wikipedia article: UWB transmissions transmit information by generating radio energy at specific time intervals and ...

Can I add a center-frequency parameter for my noise generator flowgraph, is there a different noise source that has this parameter other than the generic noise source block?

i got a morse code , someone can translate for me , i come from HK. link : https://www.facebook.com/1107747729381260/videos/3027350677292028/ many thanks !

Lately I've been thinking about weak signal communication on HF. Very weak, like weaker than even WSPR could achieve. It would be nice if one could simply take any existing modulation and slow it ...

I am working on space-ground networking for a Cube Satellite, and one of our candidate Layer 2 protocols is AX.25. We haven't settled on a physical layer, but it's likely to be some form of quadrature-...

In Portugal to transmit one must take a cat 3 exam then wait for 2 years to take the cat 2 exam. While this 2 years go by one cannot emit on his station. I find this rather annoying. Is there any EU ...

On our local Relay there are from time to time transmissions, where only static can be heard. Most transmissions via relay can be heard clearly. What could be the cause of this?

I want to understand, as most rocket uses LAN cable and switches to communicate between stages. Is it possible to replace with WiFi? Although it's will be complex system but one idea to make each ...

I want to extend WiFi signal using a passive repeater between two isolated boxes (have to make both box wireless). Transmitter antenna from box A is placed in the gap between box A and B. In the same ...

I was trying to DIY a VHF/UHF diplexer, and got some weird readings from the VNA. By debugging I reached this trivial circuit: Which has the following frequency response: I'm trying to figure out ...

My Hy-Gain TH6DXX antenna has been up on a tower about 20 years, with excellent results. Suddenly, the gain of the antenna is off the side; in other words, when the boom is broadside to the ...

Looking to take up learning understanding everything from basic electronics to how today's wideband radios work, so that I can build my own radio systems (not just ham radios), and talk radio concepts ...

I've got a week-old TYT TH-9800, a quad-band (10/6/2/70cm) mobile, Chinese knock-off of a Yaesu HT-8900. So far, I love it -- several times the power of my HT, and a better antenna actually outside ...

I'm looking for info on demodulating both sides of an ISO14443 communication using a cheap SDR, preferably an RTL-SDR (R820T2+RTL2832U). The application is passively monitoring an NFC exchange for ...

I was wondering what calculations would need to be performed to find out if a receiver will blow out in the given conditions. Portable AM receiver with ferrite rod antenna 200 ft away from MW antenna ...

I conducted an experiment today using a prototype copper wire 2m dipole at a ground level base station (noted on images) and a FT2D HT with an SRH77CA antenna. I recorded my transmissions using a ...

I know the characteristic impedance can't change because it's determined by the physical properties of a transmission line. But the impedance seen when there are standing waves changes along the ...

How is frequency selection (tuning) accomplished in a direct conversion receiver ? A crystal filter can't be used is that correct ? Because there is no IF to mix with the incoming frequency band ...

What are the advantages for a receiver that uses an IF compared to direct conversion ?

So i want to build my very own transceiver, not looking for anything worldwide, just local but i do have a background in arduino and some electrical engineering, what tutorials would you recommend?

This is a rather common belief among amateur radio operators, but is it true? A NEC analysis provides some insight on this concept.

I am wondering if I can use that dvb-t device to listen 48-836 mhz? if it's no, why? thanks..

Around my location, there is an odd signal near 50.145MHz (at this moment it seems centered around 50.14735MHz but that changes as the day progresses). Other amateur radio operators in this city also ...

I found out a while back that, as things currently stand with the FCC, if you take and pass all three license class exams in the same sitting, you get a so-called "two by two" or 2x2 call -- two ...

Last year, I planned to make a double-balanced mixer covering the entire 3-30 MHz band as an upconverter for my RTL-SDR receiver, mainly for learning RF circuits and ham radio. Naturally, it requires ...

Do resonant antennas actually resonate (in the lumped circuit sense, exchanging stored energy between inductive and capacitive elements at a natural oscillation frequency)? If so, can this resonance ...

Does an antenna tuner remove standing waves from a transmission line ?

What is the algorithm or circuit needed to generate a (vintage?, retro?) crossed-ellipse display from RTTY and/or 2FSK signals? (as per the (obsolete?) questions in some FCC exam pool) (assume ...

Resonance in electronic means: reactance of zero. (maybe wrongly/correctly someone's calling the minimum VSWR, the resonance of antenna! and this cause confusion) I've heard in Antenna Design for ...

I found the below uhd_two_tone_loopback example (which is one of the gnuradio provided examples) and I am trying to run it, it runs but I can't receive signal. EDIT: I mean when I run the program I ...

I want to locate a small ball in the air 1000 times a second. The ball is thrown from the ground and then flies in the air for 0.5 seconds until it lands. Distance from the location instrument is 1 ...

I have a raspberry pi 3b on my roof (in a plastic box) with two SDR sticks attached to it. On the raspberry pi the "soapysdr" program runs. ...

I'm thinking about buying a 70' self supporting tower that I can see had a little rust here and there. Besides minor rust is there anything I should ask the seller before I buy?

The ITU's International Morse Code recommendation ITU-R M.1677-1 specifies a "Full stop (period)" as ".−.−.−", however it falls short of specifying a decimal point. Even the examples, though they ...

I am a licensed ham looking for a UHF/VHF handheld transceiver kit. Unfortunately so far I was only able to find broken links, i.e. Ten-Tec used to produce exactly such a thing but they just don't ...

I'd read that the current theory of how lightning rods protect a house, antenna tower, or other structure is by preventing lightning from striking -- that is, the sharply pointed rod lets charge ...

I have just changed from a ground mounted Vertical antenna , to a MFJ-1796 Vertical antenna, due to not having big enough ground to bury as many verticals as recommended. So far what I have found is ...

I have designed PCB's in the past, but need to draw a constant 50 ohm impedance track on the project I'm planning. I know the calculations for (for example) a coplanar wave and how to get a straight ...

Will the bandwidth be doubled ? And will the impedance be halved ?

Using a sensor and procedure discussed in my article, I made the following plot comparing the magnetic field strength along a 30m-band half-wave dipole fed at center and one end. Key points include: ...

In the below simple qpsk_tx_uhd flowgraph I am trying to create a slider to control the number of samples but got a bit confused with which parameter I should be ...

One of the things I need to do to put my Heathkit SB-102 into service is connect a microphone. I've got a suitable crystal mic, with four conductors in the cable -- two for the mic element, and two ...

Some transceivers come with a TRS plug input labeled "key". When wiring my paddle or a straight key for these TRS connector inputs, is there any current standard for which key connection goes to ...

I was reading these lecture slides: https://web.mit.edu/6.02/www/f2006/handouts/Lec9.pdf and I tried to implement some of the schematics shown there in GNU Radio. On page 3 the author describes how ...

I'm reading about using software-defined radio for picking up ADS-B signals at 1090MHz. There is this blog which considers (among others) a setup as follows: ...

I previously asked a general question about noise reduction, but none of the answers mentioned this specific method or algorithm. (the noise reduction button on some radios and DSP software seems to ...

I've designed a two element UHF cubical quad. It was designed to resonate at 385 Mhz. I used 0.1mm thick and 1cm wide copper tape instead of wire to lower the antenna Q. I used PVC electrical conduit ...

My 20 meter inverted vee dipole is fed with 56 feet of 50-ohm coax. The SWR measures 1.2 at the center of the band. According to http://arrl.org/grounding a balanced antenna doesn't need a ground, so ...

I was trying to set up packet communication using examples in gr-digital/examples/uhd_packet_tx and rx. uhd_packet_tx is doing fine, but on receiver side(uhd_packet_rx) is freeze when i check up the ...

I have a question, right before purchasing SDR for some tests: Commercial hardware for bluetooth (even Ubertooth) allows you to receive packets on a 1MHz channel. Which practicaly means that if you, ...