[OZAPRS] HF APRS

[Glen English VK1XX]

no, there is none of that crap.


On 18/12/2017 3:02 PM, Andrew Rich wrote:
> Is there a requirements spec
>
> Is there a method of validation
>
> Sent from my iPhone
>
>> On 18 Dec 2017, at 1:17 pm, Glen English VK1XX <glenlist at pacificmedia.com.au> wrote:
>>
>> Yep
>>
>> It's ready to go. But I have to get work done this week, got to go to sort a few things out at a few sites. I need to get some python code written before going to site tomorrow.
>>
>> Over the weekend I remembered how it all works (it's a modem I wrote 4 years ago) , and modified a few blocks to reduce the CPU usage for this narrow band application, and also I added a block to generate IQ baseband signals from real input (radio output) , so it can use a standard radio.
>>
>> Compilation targets are x86 and ARM+NEON... If compiling for ARM, it is HEAVILY NEON optimized as it had to run on a certain platform ... (oDroid) .
>>
>> It searches through a specified bandwidth, throwing as many cores at it  as you tell it to, each core gets a chunk of spectrum to work on.  Roughly 50mS per second processing time per 2kHz of searching BW  on a 3.5 GHz i4670k single thread. Will run on a Odroid C1, C2, XU4 etc. might run on later Pis, never used them...
>>
>> Sync can be acheived at about 9dB below what is required for a decode (~ 1dB SNR), the modem can decode multiple transissions simultaneously in the passband and used a 1/5 rate LDPC code. Modulation is D2BPSK (2nd order diff ).
>>
>> g
>>
>>> On 18/12/2017 1:30 PM, Graeme wrote:
>>> Glen English has stated that he is working on something new for HF APRS that should be a lot better than what’s currently available.
>>> Graeme 2HFG
>>> *From:* Gerard Hill
>>> *Sent:* Monday, December 18, 2017 11:25 AM
>>> *To:* Australian APRS Users
>>> *Subject:* Re: [OZAPRS] HF APRS
>>> PAs - as in Power Amplifiers, Andrew.
>>> In the past I've run an IGate using PSK63 and GFSK63 using software called APRS Messenger <http://www.crosscountrywireless.net/aprs_messenger.htm>.
>>> These modes have great performance even without Forward Error Correction.
>>> Availability for mobiles is limited although there is a standalone modem for PSK63 available called FreeTrak63 <http://www.ringolake.com/pic_proj/FT63/ft63_page.html>.
>>> Some info on these modes from WA8LMF here <http://wa8lmf.net/APRS_PSK63/index.htm>.
>>> Be interesting to know more about what Matthew is referring to.
>>> Cheers,
>>> Gerard - VK2IO
>>> On 18 December 2017 at 11:01, <vk4tec at tech-software.net> wrote:
>>>
>>>     What is “Pas”
>>>
>>>     Whats coming ?
>>>
>>>     *From:*OZAPRS [mailto:ozaprs-bounces at aprs.net.au] *On Behalf Of
>>>     *Matthew Cook
>>>     *Sent:* Monday, 18 December 2017 9:22 AM
>>>     *To:* Australian APRS Users <ozaprs at aprs.net.au>
>>>     *Subject:* Re: [OZAPRS] HF APRS
>>>
>>>     I'd wait until early next year and see what's coming in terms of
>>>     HF ARRS, plans are a foot.
>>>
>>>     73
>>>
>>>     Matthew
>>>
>>>     VK5ZM
>>>
>>>     On 18 December 2017 at 09:48, Robert <rbaker at bigpond.com> wrote:
>>>
>>>         Hi All.
>>>
>>>         Just a quick question on HF APRS.
>>>
>>>         I have seen people chatting about modified FSK modem used
>>>         directly onto Pas. My question is do I use these modified
>>>         modems when I directly use say IC-706 mk2, or will a TT4,
>>>         Opentracker do the job.
>>>
>>>         Thanks in advance.
>>>
>>>         Cheers
>>>
>>>         Robert
>>>
>>>
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