Amateur Radio Stack Exchange
Amateur Radio Stack Exchange

Questions tagged [packet]

Questions related to sending digital data over amateur radio including hardware, protocols, and related software.

What is Packet?

While the term can apply to a specific digital mode, it is often used a general label for digital data modes in ham radio.

Packet

The term "packet" refers to "packet switching", the basic structure of the network protocol used to transfer information. This is the same basic protocol that runs the Internet. In fact, the common packet protocol is AX.25 a derivation of the Internet's X.25 protocol.

As one of the first "modern" digital modes, packet radio transmits data in groups or "packets" of 10s or 100s of bytes. This allows improved throughput and error control. Transmission speeds typically range from 300 bps on the HF bands to 1200 and 9600 bps on VHF or UHF.

Other Digital Modes

PSK31 is probably the most popular keyboard to keyboard digital mode in use today. PSK31 is normally generated and decoded using PC soundcards with one of many available software packages. PSK31 occupies very small bandwidths (approximately 100 Hz) and offers effective communication at low power. PSK31 uses Phase Shift Keying for data encoding

RTTY (radio teletype) is the original keyboard to keyboard mode, based on the 5-bit Baudot code and it began with mechanical teletypes. It is still a popular communications mode, but now uses PC soundcards for coding and decoding, using 170 Hz frequency shift keying at a 45.45 baud rate -- 60 words per minute.

For More Information

There are many many others. See: HF Digital Modes on Ham Universe for a tabular list of the more popular software packages and the modes they support with links.

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Is packet radio possible on Baofeng UV-5R and similar HTs?

I am curious to know if it is possible to do packet radio on VHF/UHF using the UV-5R... I have seen some invasive hardware hacks, but without modifying the radio itself (firmware, hardware) it's my understanding that you can only toggle send/receive…
user400344
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How To Join Packet Radio BBS

I'm a complete newbie here, and on the Southeast Coast of the USA. I don't even own a ham radio yet. Some preppers and I got to talking about a dystopian time of Internet collapse where shortwave radio might be an important factor of survival. This…
Radio1
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How do I discover APRS coverage?

I'm considering adding simple APRS transmitters to my vehicles. I'd rather just put one in and forget about it, but I understand there are areas of the US where a stronger transmitter would be required to successfully send an APRS update…
Adam Davis
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Why does the FCC put restrictions on symbol rates?

This answer claims that Mostly, on HF, the FCC has chosen to limit modes of transmission and symbol rates rather than bandwidth Why does the FCC limit symbol rates?
Geremia
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What frequencies should I listen to for packet radio?

I just obtained a really old packet TNC and hooked it up to the computer, and it appears to work. Is there a standard packet calling frequency on 2 meters? I would like to see if there is packet activity in my area, and if I can start some…
Skyler 440
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LoRa radio transceiver for PtP mesh?

I am very new to general RF/radio in general other than basic WiFi, but I'm looking at the feasibility and cost of a long range (>200M between nodes, sometimes probably 500+M) in flat terrain, relatively low power (solar + 12V SLA, short term usage)…
Drizzt321
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Can a Yaesu FT-7900R be physically connected to both KPC-9612+ ports?

The Yaesu FT-7900R has a single data port (mini DIN 6-pin) for 1200 and 9600 bps TNCs. Page 10 of the manual states: In accordance with industry standards, the signal levels, impedances, and bandwidths are significantly different on 9600 bps as…
Jacob
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APRS: WIDEn-N vs. TRACEn-N

The suggested APRS digipeater path is WIDE1-1,WIDE2-1 for the most use cases. According to the specs, this ensures two retransmissions by fill-in / regular digipeaters around the sender, without the digipeaters adding their own callsign to the…
Georg DO1GL
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Using Direwolf with multiple radios?

I'd like to play around with ax.25 connections. It seems that if I have more than one radio (operating on different frequencies) that I would want to have multiple ax.25 interfaces. Direwolf creates a /tmp/kisstnc symlink to the KISS pty device,…
larsks
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1200 baud packet radio can't communicate

I'm toying with a simple 1200 baud packet radio I built. I'm attempting for it to be compatible with APRS, which uses the Bell 202 signaling, 1200Hz for mark and 2200Hz for space, which I assume map to 0 and 1 respectively. However it's not…
Adam Davis
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AX.25 on macOS (aside from APRS)

I'd like to send raw AX.25 packets from a macOS PC using a KISS TNC (mobilinkd TNC2). I've sent APRS packets with this set up using Xastir, but I'd like to send other information besides just APRS (i.e. put my own information into the AX.25…
watkipet
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How can I generate a list of APRS IGates on 30m?

I am investigating using a Tiny Trak 4 with my portable HF radio to self-spot on SOTA activations via APRS on 30m. I usually self-spot via a text message. When I don't have any cell coverage, I can sometimes spot using APRS on 2m. I am looking for a…
Malcolm VE2DDZ
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Use ham to broadcast GPS RTK correction data

I am involved in a precise positioning project that uses Real Time Kinematic (RTK) for cm-accurate positioning. We use unattended base stations that provide real-time corrections for mobile rovers. The corrections can be used within a radius of…
Kozuch
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Where is the Multi-Drop XKISS / BPQKISS spec?

In packet radio, AX.25 is a fairly common layer-2 protocol. Many TNCs implement AX.25 in firmware, so the operator interfaces to the TNC with a serial port, using the TNC's firmware from a shell-like interface. Many TNCs also allow a "raw mode"…
Jacob
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Are there any Alternatives to Packet Radio for sending digital data?

Recently, I asked a question about using an Arduino to send packet radio. I noticed that the top record speed for packet radio is 1 megabit/second, on a modified radio. Someone mention on stack overflow that the normal speed is around 120…
itisyeetimetoday
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