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13 votes
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Resort FM radio station

I believe you have encountered a Part 15 radio station. United States Code of Federal Regulations, Title 47, Part 15 (47 CFR 15) covers such things as garage door openers and the like. As such, ...
SDsolar's user avatar
  • 2,089
9 votes
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FT8 callsign/maidenhead compression encoding

You can find the code in packjt77.f90. Callsign encoding (for "standard" callsigns that don't require hashing) is in function pack28. A quick summary: ...
hobbs - KC2G's user avatar
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8 votes
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Calculating satellite passes without an internet tracker?

The simplest might be to use an app. On Android, Heavens Above, a product of the 25-year-old website of the same name, stores the orbital elements of the satellites of interest, and does the pass ...
tomnexus's user avatar
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7 votes
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What does exclamation mark mean in FT8 CQ calls in WSJT?

That is something that is activated by "Show DXCC entity and worked before status" (selectable on the "Settings" > "General tab"). From the manual: When this option is checked WSJT-X appends some ...
Pablo Fernandez's user avatar
5 votes

AX.25 on macOS (aside from APRS)

Xastir isn't bad at all but I recently encountered something called YAAC (Yet Another APRS Client). On it's site it states the following: YAAC can be used as a stand-alone APRS client, an APRS RF-...
Tmanok's user avatar
  • 161
5 votes
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Open Source Library for Digital Mode

What you describe is Software Defined Radio! Hurray! So, everyone having read my answers knows: I'm a GNU Radio fanboy. GNU Radio has to be understood as the Free&Open-Source LEGO of Software-...
Marcus Müller's user avatar
5 votes
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How to read ID-51A GPS logger data

This is standard NMEA data format. The GPS is configured to provide the following NMEA strings: GPGGA, Essential fix data, time, location, quality of fix, altitude GPGSA, Dilution of precision and ...
Adam Davis's user avatar
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5 votes
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What dot means in JTDX FT8 received messages?

Found on the JTDX groups.io (link won't work without login, unfortunately): sybmol • - this operator loaded his log into LoTW symbol ° - this operator loaded his log into LoTW and this is Hint ...
hobbs - KC2G's user avatar
  • 12.5k
5 votes
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Is there a way to get FreeDV output level to follow the input audio amplitude?

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 ...
Marcus Müller's user avatar
5 votes
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wsjt-x problems with windows 11

With windows 11 there is a new feature "enhanced audio" Windows 11 provides additional features to improve the sound quality with more bass, virtual surround, room correction, and loudness ...
Paul Brennan's user avatar
4 votes
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Line of sight from geographic/map data?

I've used this one several times. added: Go to the graphic under: Surface Elevation Tool. Scroll (zoom out to speed things up) OR use the search to get to your geographic area. Search somewhat ...
mike65535's user avatar
  • 1,035
4 votes
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How can I decode SSTV with only macOS software?

MultiScan 3B works fine in terms of decoding. This being said I had some issues making it work with my external sound card for transmitting SSTV. For some reason transmitted images turned out to be ...
Aleksander Alekseev - R2AUK's user avatar
4 votes

Problem with sample rate

512 samples should take 256 microseconds, so your times look about right. The exact time it takes to execute those lines of code will depend on the rest of what your computer is busy with. And it's ...
tomnexus's user avatar
  • 11.3k
4 votes

Problem with sample rate

The RTL-SDR interfaces to your computer via USB. The USB interface and driver will buffer the data and send it to your software at the requested sample rate on average (baring underflow due to ...
hotpaw2's user avatar
  • 13.4k
4 votes

POTA and SOTA Spotting networks?

I don't know about POTA spots on pota.app, having not participated in POTA, but I presume that it's like SOTA spots on SOTAwatch. SOTA spots are on a completely different network than the DX spotting ...
rclocher3's user avatar
  • 9,242
3 votes

Tytera MD-380 software (DMR radio software) not working on Windows 10

I had the exact same issue on the MD390 and it took some very frustrating attempts to make it work. Turns out its just that the software is just doesn't have an intuitive UI. Hopefully this will help ...
Kerry Hatcher's user avatar
3 votes

4NEC2 - Radiat-eff. vs. Radiat-power

I just did a bit of tinkering with 4NEC2 and I've got an answer. The Input power is the power generated by the source, and ignores all losses. It might also be called "Total power". The "Radiat-...
Hamsterdave's user avatar
  • 1,844
3 votes

4NEC2 - Radiat-eff. vs. Radiat-power

I'm a NEC2 user, never used 4NEC2, but I think it's the same engine underneath. The radiated efficiency is low because either: - a lot of power is absorbed by the ground, or - you have a structure ...
tomnexus's user avatar
  • 11.3k
3 votes
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Can one modify footprints in Gpredict?

The footprint calculated by gpredict (and other satellite tracking software) is the area from which the satellite appears above de horizon (or, equivalently, the patch of earth seen from the satellite)...
Juancho's user avatar
  • 1,154
3 votes

WSJT-X V2: How to identify stations already logged?

Set your "New Call" to one color and your "CQ in message" to a different color. My new call CQs are green and my "CQ in message" are light red. The light red indicates that I have worked the station ...
Cecil - W5DXP's user avatar
3 votes
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ax.25 error shown in direwolf. Fails on channel 8, then 2, then works

This is issue #42 on Direwolf's GitHub page. https://github.com/wb2osz/direwolf/issues/42 To work around it, put the interface into CRC mode "none" with a command like this: ...
Mike Playle's user avatar
3 votes

Line of sight from geographic/map data?

HeyWhatsThat is a free web app that can show you the view from any location and elevation. From what I've seen (I haven't used it seriously), it's a bit clunky but it does the job. You can also see a ...
Kevin Reid AG6YO's user avatar
  • 24.6k
3 votes

Line of sight from geographic/map data?

Google Earth Pro (now free. $0) has a Viewshed tool. "A viewshed is the geographical area that is visible from a location. It includes all surrounding points that are in line-of-sight with that ...
Dan Jacobson's user avatar
3 votes

How do blind hams operate?

I'll answer the first part of your question, Ronald. I once witnessed a blind ham (WD8PIC) operate. His solid-state transceiver had a speech synthesizer that audibly spoke the frequency when the ...
Mike Waters's user avatar
  • 8,023
3 votes
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Is there a freely accessible repeater database?

Since there was no such repeater listing out there, I started my own database: https://hearham.com/repeaters As a bonus, there is a service to comment on, and favorite to get status notifications ...
NoBugs's user avatar
  • 241
3 votes

Calculating satellite passes without an internet tracker?

To track the satellites, you need the Keplerian TLE orbital coefficients. Once you have those, you can track the sats without internet access. The TLE's are accurate enough for about a week. The ...
user10489's user avatar
  • 6,455
3 votes
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Open source RS41 decoder

You have to provide the -i option to invert the signal in order to decode it properly. The lowpass filter is not really required as this is a quite strong signal (...
cygeus's user avatar
  • 46
3 votes
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Store and forward system like voicemail for hams

You may like checking out svxlink. I've had success setting it up on a Raspberry Pi, interfaced with a baofeng (pls don't judge) to accomplish VM (as well as successfully interfacing with EchoLink) in ...
webmarc's user avatar
  • 4,234
3 votes
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How does AMPR work over IPIP tunnels?

FYI, I'm writing this as someone experienced with Linux IP routing, but only superficially familiar with AMPRNet. All of the routing appears to happen through ordinary Linux facilities which can be ...
Phil Frost - W8II's user avatar
2 votes

Resort FM radio station

Of interest here: in the areas under the jurisdiction of the U.S. FCC, legal unlicensed operation in the FM broadcast band is limited to systems producing a maximum field intensity of 250 µV/m at a ...
Richard Fry's user avatar
  • 2,922

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