9

There is a kind of repeater that can repeat any kind of transmission: it's called a linear translator. It's technically equivalent to an SSB receiver linked to an SSB transmitter. It works for any mode because SSB is simply a shift in frequency. Other than the change in frequency, the baseband and RF signals are linearly related. This is also why an SSB ...


6

What you're asking for is a link budget. For HF, you can use software like VOACAP to estimate path loss. There are several ways you might use the software, but to start I'd suggest: Click the antennas button, and enter the kinds of antennas you have available for each band. Drag the location markers to the relevant places. Not all 10,000 km paths are the ...


6

I figured it out. In FLDIGI I had video IDS check marked under Configure/IDS/Video. Here is the link to a video on YouTube that clearly explains what I needed to know. https://youtu.be/nwkz0GNpA0I


5

It seems that FreeDV encodes the input audio signal in both the frequency and time domains, which means that the output signal amplitude doesn't follow the input signal amplitude, but rather the output level from FreeDV is always high, even with no input audio. Nah, that's not really the case. FreeDV uses a multicarrier scheme with 14 orthogonal carriers. ...


5

You're asking exactly the right question – my receiver can't know this property of the transmission, how do I figure it out reliably – and that way of thinking makes for good receiver designs :) There's two classes of methods to solve this: statistics-based methods transmitter data assisted methods What is very common in receiver design is that you have an ...


4

That was just added by someone who's primary language probably isn't English. What they meant to say is "QPSK31, a mode that is related to PSK31, uses..." Other than that, the claim "it uses more constellation points, that's a means error-correction coding", is plain wrong. The error coding used is this, just one sentence later: A ...


4

This same problem of discriminating symbols can appear in as simple a system as transmitting an "unmodulated" binary code (2 symbols) over an AC-coupled cable (such as is used in Ethernet). If your message has a long string of 1s or 0s, how does the receiver tell them apart? The solution in either case is to use a coding which ensures that all ...


4

Troposcatter is the common mode for beyond line of sight on the 10 GHz ham band when the band is not otherwise open, good for 100's of miles. A radio with just a few watts output power and a moderate sized dish (60cm or more) gets enough ERP for troposcatter. For a few random references, check out: Pages 64-70 of http://www.mike-willis.com/Tutorial/RT%...


3

You're confusing the transceiver implementation with mode as is. Every single mode, as long as it's not used to transported to transport graphics, can be operated without a GUI. Whether or not an implementation without a GUI exists is a different question, but honestly, coming from a world that's not Windows, this is basically the standard – be it FreeDV, ...


2

The WSJT User Guide version 2.0.0, which is hosted at the Princeton Physics website, was written by Joe Taylor W1JT himself, who wrote much of the WSJT code. In the Protocol Specifications chapter there are links to QEX articles and other references, including one about the JT65 protocol. Given Professor Taylor's academic background, to me it seems safe to ...


2

$ od -txC QSOPCTDIR.dat 0000000 60 00 00 08 20 20 20 20 20 41 4c 4c 20 20 20 20 0000020 20 20 20 20 20 20 20 20 20 45 41 47 4a 44 52 32 0000040 41 55 49 20 20 20 20 20 20 20 20 20 20 20 20 08 0000060 30 20 30 00 20 08 30 20 30 00 20 08 30 19 43 00 0000100 32 30 32 30 2f 30 38 ...


2

It might be the transformers frequency response is not flat. Try replacing them with reputable units that have a published frequency response such as here. See more signalink tweaks here.


2

Listen tcp 0.0.0.0:5000 bind address already in use. This sounds like a somewhat generic error, not necessarily related to your AX.25 software itself but certainly a bummer to encounter it while setting up! What this means is the software you're trying to run wants to listen on port 5000, on all network interfaces (the 0.0.0.0 part). But something is ...


2

In this case, "allied mode" can be replace with "associated mode" or "kindred mode." The phrase indicates that there is a relationship between the two modes, BPSK and QPSK, without specifying the particulars of the relationship. "Allied mode" is not meant to convey or identify any specific technical content.


2

What SNR should I expect? Wrong question! You need to ask yourself: What's the SNR I need to still achieve my desired performance. "Desired performance" here is How much data do I need to transmit in a definite time (data rate) How long can I wait for the transmission to complete (latency) Which probability of missing the reception can I accept? Which ...


1

If you have a Ham license, and your application is for ham use, not encrypted, non commercial, and follows proper amateur radio etiquette, bandwidth, and power limits, you can. You will be also required to sit at the radio (no automatic operation for this band in the US IIRC). As for transmitting FM, I'm not sure what you mean. There are plenty of digital ...


1

Part of what makes a repeater valuable is it filters out "invalid" or weak signals. This makes them efficient in power use as it's not transmitting all the time. This makes them valuable to the users as they aren't hearing noise all the time through their radios. What makes the signal "valid" is having sufficient power, at the correct ...


1

This might be the same problem as described by LA1K in this blog post. The integrated USB hub is apparently powered by the USB port, not the radio's power supply. A powered USB hub is the solution if you don't have a USB port supplying enough current.


1

No. Part 97 (FCC rules for amateur radio) place limits on width of spectrum usage. For frequency/phase oriented modes such as AFSK, FSK, and PSK they are specified in symbol rate since increasing symbol rates (bauds) result in a widening of the sidebands created by these modes. Symbol rates / baud figures are not data rates. Multiple bits can be packed ...


1

We, ARES, send files often via VHF packet and via several HF digital modes. My favorite HF digital is based on the many modes of FLDigi, but set up the files (like ICS-213 form) using Winlink Express. On VHF, my station is part of a packet network, running 24/7. www.midgadata.net. The net also supports DRATS on the same frequency; so we can use the DRATS ...


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