VK Logger Ham Radio Forum Archive

Hi all,

FYI,

PS-63 is in the air.

Solar powered custom balloon, 25mW TX
TX WSPR, JT9 on 30m only

Dial frequency 10.138700Mhz (standard WSPR dial frequency) for WSPR, JT9.
JT9 is at 1650Hz

See HF decoding info at http://picospace.net/?cat=34

Tracking as PS-63 on SNUS http://picospace.net/tracker/new
WSPR call sign is VK3YT http://wsprnet.org/olddb?findcall=vk3yt

TX scheduling
Minute - Band - Mode - Condition
:00 - 30m - 2 mins WSPR then two x 1 min JT9 - mandatory
:10 - 30m - 2 mins WSPR then two x 1 min JT9 - if batt full
:20 - 30m - 2 mins WSPR then two x 1 min JT9 - if batt full
:30 - 30m - 2 mins WSPR then two x 1 min JT9 - mandatory
:40 - 30m - 2 mins WSPR then two x 1 min JT9 - if batt full
:50 - 30m - 2 mins WSPR then two x 1 min JT9 - if batt full

Please track, and have fun!

Andy

Just saw the post and switched the radio over and really good signals this arvo

Thanks for the Launch Andy
[edit]
Wow its sure got a tail wind 145kph at 530


len

This one is a bit higher Andy.

- David

Thanks for another Pico balloon Andy

I enjoy observing the telemetry data received from these flights.

A couple of graphs showing profiles on some telemetry stats. Battery voltage becomes very critical with temperature as we all know.

There is missing data data between 0100 and 0500 utc maybe due to server down ? not sure why.

Hopefully a wake up in sunlight tomorrow.

73

Andy is it the cold making PS-63 go to sleep when at night ? If so is the cold killing the battery or is it the electronics shutting down

13,600 m is a lot higher than the last flights
thanks
Len

Yes the battery would be the first to go, but we have seen the case where the payload transmits but the cold temp causes too much frequency drift to be decoded.
The higher altitude hopefully will keep the balloon out of most bad weather!
Andy


Sent from my iPhone using Tapatalk

Thanks Andy
Was up the other night late and saw Bob ZLRS had a decode twice in the middle of the night on JT9 yet nothing on wspr .
2.7 v from memory was Battey volts

Thanks Len

VK4ALF wrote:... Was up the other night late and saw Bob ZLRS had a decode twice in the middle of the night on JT9 yet nothing on wspr

Hi Len,

The extreme cold induced drift on the WSPR signal was non-linear and would have been near impossible to track over the 2 minutes.
The JT9 drift however was near linear and could be tracked fairly successfully by shifting the RX dial by 1Hz every 3 seconds.
Here are all the successful 'drifty signal' JT9 decodes and their telemetry 'translation':
0532 -5 0.3 1620 VK3YT0L730M50 ... 151.2kmph 7, 3, -60°C, 2.787V 0V
0602 -6 0.3 1617 VK3YT0L630LK0 ... 151.2kmph 6, 3, -60°C, 2.706V 0V
0603 -5 0.4 1607 1-ZB313 7PW20 ... -37.399,-135.81,13430m, 0054
0702 -3 -0.8 1621 VK3YT0L630L60 ... 151.2kmph 6, 3, -60°C, 2.664V 0V
0703 -4 -0.7 1610 1-BQ31Z77L.12 ... -38.392,-134.495,13269m, 002C
0803 -7 -0.1 1625 1+SP32QJ7L 0G ... -39.443,-133.097,13266m, 0010

As you will be aware it is very cold at high altitude, typically:
The night time temperature telemetry from the previous flights at 9500m ASL was around -45C and the batteries were marginal at that temperature. It is amazing that a battery which is probably only spec-ed to work reliably down to -20C or so was still working at -60C!

73,

Its really remarkable that the battery is its working in such extreme temperatures

I see you just got a decode at -37.5 deg ...WOW .

Well its passes South america and heading for South Africa at a great rate of knots
I Could just see the JT9 on the waterfall faintly and not good enough for a decode tonight

Thanks for the explanations Bob and Andy

Wow a nice long distance spot by JQ2WDO