Questions tagged [receiver]

Use this tag for questions about the theory and structure of receivers.

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4
votes
2answers
145 views

Use noise figure and gain to calculate weakest signal radio can receive?

An FM radio receiver, using a 1 kHz tone at 3 kHz deviation has a 12 dB SINAD (Signal To Noise and Distortion) of -116 dBm. I would like to increase the 12 dB SINAD sensitivity of the receiver to at ...
4
votes
1answer
798 views

How to make an inductor?

I am a high school student and am making a project on FM receiver for class 11. I am following this circuit diagram: The L2 in this diagram is a 22µH RF Choke. The part listed in the website has the ...
3
votes
2answers
666 views

Understanding WFM modulation

I am using "HDSDR" software to demodulate a WFM broadcast ("Classic FM" in the UK, on 100.1 MHz, 192 KHz bandwidth). I'm using an "SDRPlay RSP1" software defined radio and a cheap indoor discone ...
3
votes
3answers
2k views

How to receive a signal from multiple sources simultaneously (helical antenna)

I'm working on a system (theoretical at the moment) whereby I wish to receive data from multiple sources all transmitting at the same time. I've read that a helical antenna is capable of this. I'm ...
3
votes
3answers
722 views

Any SDR radios that receive FM BCB

Are there any software defined receivers capable of receiving Regular FM broadcast band stations and displaying a waterfall of the band from 88 MHz to 107 MHz or a significant portion of that range?
3
votes
3answers
373 views

Iskra sst 2030 radio speaker plug

I was asked by a friend to take a look at an old 70-80s Iskra sst 2030 (ex Jugoslavian-slovenian company) radio. The radio seems to work fine but I can't understand which plug it uses for speakers. ...
3
votes
5answers
863 views

“Local oscillator generates a frequency twice lower than received signals”. Why and how does it work?

I would like to construct the following receiver: I have a fair knowledge about a receiver building blocks. I have previously build small receivers. In the description it say: The local ...
3
votes
4answers
942 views

Is it normal for mini shortwave radios to not have any reception in a major city?

I'm new to radios. Just bought the mini Eton which has FM/AM/SW and while FM & AM work I have never received a single station on SW1 (5.9 - 10 MHz) or SW2 (11.65 - 18 MHz). Is that normal? Will ...
3
votes
2answers
2k views

In SSB how do receivers calculate the frequency offset without a carrier?

On page 2-9 of the ARRL Ham Radio License Manual, it discusses how in SSB one of the side bands and the carrier are suppressed to conserve power and bandwidth. Given the explanation of how AM works, ...
3
votes
1answer
81 views

What's the use case behind long AGC constants?

So my shortwave radio has adjustable AGC constant with settings between 0.1 s to 8 s. I always find myself using the fastest AGC settings. Often, I experience 20-30 dB fades and if I use the slower ...
3
votes
1answer
608 views

Idea for better reception in crowded city

I am living in crowed area of a city. It is impossible for me to set up an antenna outside the apartment. I receive signal inside the room. I have a funcube dongle pro+ and some RTLSDR, the picture ...
3
votes
2answers
199 views

How to identify a practical HF communication receiver?

I've recently purchased a Hallicrafters S-120 -- 4-tube superhet receiver from the 1960s, continuous tuning from 540 kHz to 30 MHz, bandspread control, and a regenerative IF that doubles as a BFO for ...
3
votes
2answers
1k views

Scanner radio for 433MHz locator beacon

I am looking for a recommendation of an inexpensive scanner radio that should be used to locate animals equipped with 433MHz locator beacons. The beacons (based on DRA887TX) will send periodic tones. ...
3
votes
5answers
536 views

Crystal set as wireless earphone

Reading about a 'necklace' coil inducing a strong alternating audio current (using an LM386 f.i.) into a magnet inserted in the ear canal set me thinking. The problem is that the magnet has to be ...
3
votes
1answer
38 views

Tradeoffs: varicap vs. air variable capacitor for Rx bandpass?

What might be the tradeoffs between choosing varicap diodes versus air variable capacitors in the design and construction of tunable bandpass filters for HF receivers?
3
votes
2answers
389 views

How do I listen to the amateur radio satellites?

I'm new to amateur radio, and I would like to listen to those satellites in the orbit. Where do I start? What types of amateur radio satellites exist?
3
votes
2answers
169 views

Determining whether signal meets the 12 dB SINAD voltage

The specification for a certain radio receiver says: Typically 12dB SINAD NBFM for 0.15uV at 145MHz. If I understand correctly, this means that the received radio wave should have a voltage level of ...
3
votes
3answers
316 views

78.5MHz AM receiver self-oscillation

Circuit appears to be working but very easily breaks into oscillation - sometimes just getting up from my desk triggers it, or while tuning, and sometimes after a few seconds with no disturbance that ...
3
votes
1answer
257 views

What is this odd data/screeching/fuzzy signal?

I was listening to a commercial FM radio station on 100.9 MHz, and this intermittent weird sound kept coming through it. Here is a recording of it. The audio starts at about 15 seconds. It sounded ...
3
votes
1answer
267 views

Seeming conflict in the definitions of dynamic range

As I understand it, dynamic range is the difference in dB between the strongest and weakest signal discernible by your receiver. So, the larger the dynamic range, the better, which seems intuitive. ...
3
votes
2answers
621 views

How to make a “you're getting warm/cold”/“fox hunting” game based on RF signals

I would like to build a system in which the emitter emits omnidirectional RF signals, and the receiver gets a stronger signal (it does not have to be accurate) with a) closer distance from the emitter ...
3
votes
2answers
245 views

What are some shortwave radio stations I ought to reliably receive in New Hampshire?

I recently bought a Techsun PL-660 radio and it picks up virtually nothing on SW. I fear I may have a dud.
3
votes
1answer
155 views

FFT frequency shift corrupting phase

I have written a Software Defined Radio. I take I/Q audio into the computer at a 192K sample rate and perform a 4096 sample Complex FFT. I display the spectrum (PSD) to the user so they can pick the ...
3
votes
1answer
64 views

Carrier wave timing

I'm not really too technical when it comes to radio, but I understand that in AM, a shortwave radio generates the carrier frequency so that it can mixed with the received station and then removed, ...
3
votes
1answer
650 views

Receive antenna design for a small apartment

I am looking to make a simple receive antenna from some wire, and I have some questions about resonance. Being that this wire can only be so long (about 3 meters maximum, as it must fit inside my ...
3
votes
3answers
4k views

What effect will placing two receiving antennas next to one another be on the received signals

I'm planning on using 2 receivers that operate on the same frequency. So there's no confusion I'm talking about WiFi signals (but I'm trying to do some cool amateur radio stuff with it!) so the ...
3
votes
2answers
1k views

2m Homebrew Receiver - Chip for frequency [closed]

I am a new HAM trying to design a small, cheap 2m receiver. I've been looking up different circuits and homebrew tutorials, but the closest I seem to find to what I'm looking for seems to always use ...
2
votes
2answers
600 views

Can a FM tuner (receiver) be detected and triangulated?

In movie "6 Below", based on a true history, a lost snowboarder at Mammoth Mountain (California) is located by search and recuse when they detect and triangulate a signal from his MP3 player that also ...
2
votes
2answers
176 views

What equipment and software do I need to read raw civilian GPS signals on my Mac?

This is a hobby project to learn more about GPS technology.
2
votes
3answers
458 views

What causes my direct conversion 80m receiver to receive AM broadcasts?

I am making a Direct conversion receiver from this circuit at this website. I made it for the 80m band and I changed: The frequency of VFO to about 1.75 MHz L1 and L2 to a bandpass filter for 80m ...
2
votes
1answer
378 views

Detecting the listeners

I wonder, if a broadcasting radiostation can detect, how many receivers are tuned on it, and if it possible - how exactly this detection is happening? Thanks.
2
votes
2answers
136 views

How can I listen to channels above 1710kHz?

I hear of channels at, for instance, 4625kHz and I want to check them out but the only radio I have is the one in my car which only goes up to 1710kHz. What kind of radio do I need to listen to ...
2
votes
1answer
87 views

Receiving an Coded Odd Signal at 137.25MHz but don't know what it might be. It can affect my detection on NOAA 19. Need help

I am a newbie trying to detect NOAA 15, 18, and 19 satellites, which have downlink frequencies between 137 MHz and 138 MHz. I am using an SDR dongle and attached a photo of it to this post. Of course,...
2
votes
2answers
140 views

How to safely connect a digital output to a receiver's antenna input?

Suppose I have a 3.3 or 5V GPIO digital signal (from an Arduino or Raspberry Pi, etc.), periodically toggling at some HF or VHF frequency. Since it has such a "dirty" spectrum, I don't want to hook ...
2
votes
1answer
1k views

What parts / procedure do I need to build a UHF receiver that can connect to a standard pair of headphones

I have a low power wireless microphone (10 - 50 mW) with a large receiver designed to connect to a mixer/sound system. The mic transmits in the UHF band between 530 and 860 depending on the band (see ...
2
votes
1answer
175 views

How does this circuit work? Why is the antenna connected to the output of the amplification stage?

What is the function of the configuration of R1, C3,C10 and R3? How does the LC tank in this circuit work?
2
votes
2answers
706 views

What's the difference between the normal and S-meter squelch in IC-2730?

I recently obtained an IC-2730E and can't figure out the difference between its squelch options. Unfortunately, the user manual isn't very helpful. The squelch option had 3 types: off, attenuation and ...
2
votes
2answers
198 views

How much EMF does a typical scanner put out?

I am not terribly interested in hearing about whether or not EMF/RF is hazardous to ones health (as this is frequently discussed in my house). What I would like to know is; how much EMF/RF does an ...
2
votes
2answers
2k views

Simplest, smallest antenna for tuning WWV, WWVH?

I'd like to perform some simple receiver testing and calibration (mostly for frequency variance, not signal strength) and have been told WWV/WWVH transmissions can be found throughout most of the US. ...
2
votes
3answers
169 views

Will a “crystal set” work with an untuned RF amp stage?

In my ongoing process of building up to a homebrewed general coverage receiver/transceiver, a first step might reasonably be a crystal set, where a tuned circuit and simple, or even improvised, ...
2
votes
1answer
224 views

Frequency Display for Old Tube Radio

I have a Hallicrafters S-120 1960s vintage vacuum tube receiver (an "All American Five" superhet with solid state rectifier replacing one of the "five" tubes). It works well, doesn't have excessive ...
2
votes
1answer
64 views

Baofang uv-5rA/ repeater trouble

I programmed my Baofang UV-5RA radio to my local repeater about less than a 1/4 mile away. When I cue the mic and release, I get a signal from the repeater. However, I can only hear people if I have ...
2
votes
1answer
696 views

Receiver using a NE602 oscillator-mixer not working

I built a CW receiver using NE602 for the 20m band. Unfortunately, I do not receive any CW or SSB signals, only some noise and sometimes broadcast stations. The schematic here shows the circuit that ...
2
votes
1answer
43 views

Poor reception on single AM channel

My car stereo has terrible reception on a single AM station. Other cars get the signal fine and other channels on radio are received fine. I have contemplated some sort of booster for the antenna or ...
2
votes
2answers
203 views

SkyStar S2 has a mac address, for what? [closed]

Hy just a "stupid" question, I bought a technisat skystar s2 pci card. Can any body tell me why this thing has a mac address printed on it? ^^ And the mac address can even been looked up. (00-08-c9-xx-...
2
votes
1answer
169 views

FSK real world application BER

I have designed a receiver for FSK reception in 434 MHz ISM band. For this I used USRP1 and GNU Radio. Now, I would like to measure performances of my receiver. For this purposes I did following: I ...
2
votes
3answers
1k views

Are there legal restrictions on radio reception in India?

I live in India and would like to know whether it is legal to listen to on the air transmissions there. I know that transmitting is allowed only in limited frequencies and strictly require a HAM ...
2
votes
1answer
78 views

How much field strength to blow out a receiver?

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 ...
2
votes
1answer
97 views

How to scan while avoiding digital/noise frequencies?

Is there an established way of scanning frequencies, while avoiding listening to digital signals or static? For example, is there a scanner on the market which will allow you to blacklist a specific ...
2
votes
1answer
115 views

feasibility of wireless passive crystal earphones

I just learnt about such a thing as a crystal radio receiver and the following idea came to my mind. I have no background knowledge on electronics nor anything related. What if battery-less earbuds ...