On receive, it uses a class-D (switching mode) audio power amp to drive the speaker or headphone jack. This amp is very efficient extending the battery life, but has horrendous levels of distortion.? This makes voice sound crappy but still intelligible. It absolutely mangles complex data waveforms.

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Thanks for your email. My end plan is to be able to do VARA? FM mobile with a hand held radio and if I have to, use a portable antenna.? Can you recommend a hand held that will work with a digirg VARA?

Paulbuchanan51@... KO4QWS?

It is utterly unrealistic to use an under-powered handheld as a mobile for data, especially if you don't use a decent external gain antenna.?? Unlike voice, data requires a fully-quieted noise-free signal at the receiving end to work reliably. The kind of signal with occasional pops, snaps and drop-outs that is usable on voice simply WON'T WORK for data.? You MUST have a? "Full smash" hard-quieted signal free of fading or multipath for data applications. It must have enough excess signal that you don't hear "mobile flutter".?

Roughly speaking, you will need two to three times the transmit radiated power? (TX power times antenna gain) for reliable data compared to usable voice over the same path.? If you don't have that kind of solid path, you will flood the radio channel with endless failed transmissions, NAKs and retries. The actual net transmission rate will be a small fraction of the claimed rate for the mode. ?

On Sat, Jul 8, 2023, 9:23 PM Rich Holtman, KD9ANU <rich.holtman@...> wrote:

Paul,

As much as I like my Baofengs for voice work, from everything that I have learned over the past 5 years regarding doing Packet (and VARA), you should expect to be disappointed trying to do VARA or Packet with Chinese HT's.? I don't remember all of the technical reasons, but these include not being fast enough to switch from transmit to receive and vice-versa, therefore data is lost, and the connection fails.? I live 9 miles from our local RMS Gateway (Packet) here in Central Illinois, it is pretty much line of sight except for a few trees, and I have made it work, but not consistently.? Need at least an antenna in the window, or better yet an outside antenna.? So I do 99.9% of my Packet work using a Kenwood TM-71, with an antenna whose base is at 25 feet.

Best of luck,

Rich, KD9ANU

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The Baofeng is a low-end? low-performance? trash radio.?? It is the ONLY radio to ever fail the ARRL's tests for compliance with the FCC's spurious emission standards.??

The problems using it for data are numerous.

It is plagued with a low-performance wobbly unstable frequency synthesizer that takes hundreds of milliseconds to shift from receive to settling on the transmit frequency, when you key up. This can cause part of the header in data modes to be lost before the TX signal is actually on-the-air and on-frequency.
??? Further, there is no TX inhibit that prevents the transmitter from producing output BEFORE the RF carrier is settled on the desired frequency.? Keying up a Baofeng actually causes a full-power carrier to "swish" across several adjacent channels before settling on your channel!? You can see this effect clearly on a high-resolution spectrum analyzer.
??? Even after it gets on frequency, it's carrier has a constant low-frequency jittering or wobbling, not noticeable on voice, that degrades data significantly.?

On receive, it uses a class-D (switching mode) audio power amp to drive the speaker or headphone jack. This amp is very efficient extending the battery life, but has horrendous levels of distortion.? This makes voice sound crappy but still intelligible. It absolutely mangles complex data waveforms. ?

Further (like all handhelds) it lacks the unfiltered flat-frequency-response receiver discriminator output present on full-size mobiles with the 6-pin mini-DIN "data" port. This wide-band receive output is essential for the higher-speeds of VARA-FM.?? (This is a reason nearly all hand helds are a terrible choice for data applications.)

On transmit, you are forced to send the TX data into the mic jack rather than into a dedicated data port.? The transmit speech chain also has a rather high level of distortion that damages data before it even leaves your antenna.? (This problem, common to all hand helds,? is just another reason why hand-helds are a terrible choice for data operations.)

I have a Zeus ZS-1 that unlike Icom 7300 and others only has 1 USB connection that shows up as a com port.

In vara modem setup I can only select the analog audio card of the PC that is not doing anything with the ZS-1.

Any tips how to get the audio routed to Vara modem????

Pedro.wyns@...? ON7WP

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I am interested in EMCOMM support for both private and public entities. However, I am puzzled by how to use Vara HF for the services using Private Land Mobile here in the US. That service is regulated by the FCC Part 90 regulations, and my reading of that section seems to indicate it allows SSB operation below 25 MHz for only voice, (J3E) not any data modes (J3D). Also, since the Vara package now capable of encryption is Vara HF, what equipment would one use for operation on PLM frequencies? It would need to be certified to Part 90 standards, I believe. Also, it seems the operation of a base station would require careful coordination with controlling agencies, as frequency assignments are based on limiting coverage to a limited geographical area so as to not create interference with other licensees using the same frequency in other areas. How would one go about getting all these conditions satisfied?
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VY 73,

Wes WB7BR

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What sort of Private Land Mobile operations use HF/SSB??? Normally, land mobile, either private/commercial, or public safety, use VHF/UHF or 800/900 MHz frequencies.

Given that today virtually all LMR activity today uses digital modulations like P25, DMR, TETRA, NXDEN, etc due to FCC narrow-banding mandate a decade ago,?? external AUDIO-based digimodes like VARA wouldn't work anyway.? With these digital radio formats, you can't just stuff audio tones from an interface or TNC into the radio's mic jack. ??
??? The radios for these digital formats normally provide their own data input jacks where the original serial data stream from the application would be combined with digitized voice into the radio's digital data transport stream. ? These types of "data" inputs are often used for GPS position data, SMS short text data for? dispatch, etc.?
??? Any encryption has to be done either by the application (email or messaging app) or in the radio's digital modulation process.? (P25 public safety radio can do this for either the digitized voice or externally-provided data for example).? [Once ANYTHING is digitized, it's really quite trivial to scramble the pattern of data bits and un-scramble them at the receiving end .]? ? "Middle-man" audio-based modulation schemes like VARA, PACTOR, etc intended to be fed into the voice channel of analog radios are completely out of the picture and irrelevant .

VHF/UHF propagation is relatively constant, making co-channel coordination predictable and practical,? On the other hand, the ever-changing and often unpredictable hour-to-hour and day-to-day long-range propagation on HF makes this kind of co-channel coordination almost pointless.