PICAXE is in Space

M

MFB

Senior Member
Manuka, good to hear that RevEd plan to make the most of the opportunities offered by the success of the $50sat. All they really need to supply is supply a front-end package for the Baofeng (eg. Yargi, LNA and cable) and a link to free sound card decoding software. As ever, the major effort will be in producing good quality documentation.

Almost forgot, package should include a small tube of glue to disable the Baofeng PTT button.
 
S

srnet

Senior Member
A summary of some of the issues raised in recent posts.

For those listening for $50SAT with a handheld the precise timing of the arrival of $50SAT need not be accurate, the beacon is only transmitted every 70 - 90 seconds, so you could miss one and have to wait 90 seconds for another. So you need to be waiting 2-3 minutes either side of the predicted time of closest approach. The very first orbit parameters, we were using those for Unisat-5, were 2-3minutes out which was flagged up. Since we have been testing and using those for object 2013-066W, the change between the very first set and the current set has been around 40 seconds, which would not have impacted anyones ability to hear it on a handheld.

I have been careful not to mislead anyone by saying that 2013-066W is $50SAT, its always been a case of it may be, and it will stay that way until we are certain. The orbit parameters for 2013-066W have changed several time in recent days (and the dropbox updated of course), the current set give us a suspicion that 2013-066W is not $50SAT, but some nearby bit of space junk, again we cannot be sure. And as I have mentioned previously its still unclear if NORAD are able to track such small satellites in the first place.

$50SAT is not tumbling as far as we are aware, although it is exhibiting symptoms of spinning on its long axis causing the polarization of the signal from the dipole to change. Anyone listening in LSB\FSK mode will readily hear this 'spin fade'.

Overcast conditions make virtually no difference to reception of signals from $50SAT. Absorption by clouds of radio waves only becomes a significant issue at 5Ghz and above.

Once $50SAT is located, it will be known in the catalogs and databases as Eagle2, as this is the name used for the allocation of the frequency $50SAT is using.
 
S

srnet

Senior Member
manuka said:
Rev. Ed are considering educational promotion of the "PICAXE Sat.",& this kit (or-ahem- DIY clones) seems a worthwhile weak signal booster when used in conjunction with a decent antenna. It may also suit general 433 MHz RX application of course.
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As we dont know how long $50SAT will last, Rev Ed could find themselves in a position of selling kits to listen for $50SAT and there is nothing to be heard.

And whilst that Ramsey kit is cheap, I do wonder how the average PICAXE constructor would manage.

That amplifier is likely intended to be built into a bit of kit. As a standalone it would need a metal screened box, with proper attention to the layout, amplifiers like that are easily turned by poor layout into oscillators.
 
Technical

Technical

Technical Support
Staff member
srnet said:
As we dont know how long $50SAT will last, Rev Ed could find themselves in a position of selling kits to listen for $50SAT and there is nothing to be heard.
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No intention here to sell kits, although we can obviously collate and publish info on setups such as the Ramsey kit if somebody who knows what they are doing (we don't!) proves that they do work.
 
S

srnet

Senior Member
I am now getting fairly reliable data packets back when range to $50SAT is around 650km, the upper limit seems to be around 950km.

This is with an LNA and hand held 7 element yagi waved around in my garden. The data packets are at 1kbps and 29 bytes long.

The orbit parameters published by NORAD continue to change, first one way then the other.

The set on the dropbox are quite 'old' by now, 7 or 8 days, but from the observed changes in frequency (due to doppler effect) the older set on the dropbox are closer to reality than the latest from NORAD.
 
P

Paix

Senior Member
GGG035.png
Not from the International Space Station, but don't those two connectors look a bit like USB connectors, CoTS technology . . . Apple white?
 
S

srnet

Senior Member
Apologies if this has already been mentioned in this thread, but is this picture showing the actual release of 'srnets' cube?
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No.

$50SAT was launched via a Dnepr rocket, not from the ISS.

And its a PocketQube not a 'Cubesat'.

PocketQubes are much smaller than Cubesats and cannot (as yet) use the same launch mechanisms .......
 
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S

srnet

Senior Member
Playing with antennas.

I was making a better feed for a large antenna, a corner reflector made of cardboard boxes and foil, and I decided to test the feed as an antenna in its own right.

Its a BiQuad, instructions and how to adjust for a particular frequency are here;

http://www.rcgroups.com/forums/showthread.php?t=1328260

Its meant to be used with a reflector, but I gave it a go without. Bit of copper wire from some solid core mains cable, shaped and soldered to a BNC chassis socket. Took maybe 15 minutes to build.

Strong signals heard on a pass this morning, closest approach was 740km, and it was still clear enough at about 1000km.
 

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kranenborg

kranenborg

Senior Member
I have noticed that in the $50SAT DropBox detailed hardware information has been added regarding the LTC3105-based MPPT control system (functional description, diagrams etc.):

https://www.dropbox.com/sh/l3919wtfiywk2gf/_7EA5vIOva/Hardware Designs

Very inspirational for all kind of very small solar-driven projects (e.g. even single-cell will work, see my post #53 in this thread). Many thanks for the info. Now if SparkFun or whoever else could put an LTC3105 onto a breakout board (Rev-Ed maybe!? , boosting solar-base picaxe projects!)

/Jurjen
http://www.kranenborg.org/electronics

PS: Corrected DropBox link
 
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S

srnet

Senior Member
I did some gain measurements on the BiQuad, comparing it to the typical rubber duck style antenna as use on the cheap Baofengs etc.

Transmitter was RFM22B at 1mW into a 1/4 wave vertical antenna, 437Mhz, field strength measured at 80M with RF Explorer.

Misc antenna 1 (Baoefeng ?) -81.5dBm.
1/4 wave vertical DIY wire -80.5dBm.
Bi-Quad - no reflector - 75.5dBm.

So the BiQuad on its own has about 6dB gain over the standard rubber duck antenna.

Holding a reflector behind the BiQuad (at 1/8wavelength distance) increased signal by a further 5-6dBm. The reflector was a bit of cardboard covered in turkey foil.
 
S

srnet

Senior Member
Low Noise Amplifier Tests

I have run some recordings of the differance a Low Noise Amplifier can make when listening to $50SAT. The test transmitter put out very weak simple tones.

I tested 3 radios, a Baofeng 5VR, Funcube Pro+ and a Yaesu 120D scanner.

I used two LNAs, the outrageously costly SP7000 (£380);

http://www.thedxshop.com/sp7000-432mhz-masthead-preamplifier.html

and the Ramsey LNA (£7);

http://www.ramseyelectronics.com/Low-Cost-440-Receiver-Preamplifier/dp/B0002NRKN0?field_availability=-1&field_browse=6290135011&id=Low+Cost+440+Receiver+Preamplifier&ie=UTF8&refinementHistory=brandtextbin,subjectbin,price&searchNodeID=6290135011&searchPage=3&searchRank=salesrank&searchSize=12

The recordings are here;

https://www.dropbox.com/home/$50SAT/LNA Tests

The Ramsey makes a small difference to the relatively insensitive Yaesu scanner, but had no benefit for the other receivers.

The difference the SP7000 makes is clear. The SP7000 is not cheap but its a fully weatherproof amplifier with automatic TX\RX switching. The switching means that you can transmit at will, whereas with the separate LNAs you can only uses them in RX mode, accidentally transmit to them and they are toast.

One very promising looking LNA (for 70cm) are the ones sold here, £55 for the kit;

http://www.g4ddk.com/

Specification is impressive, <0.4dB noise ~41dB gain, have one on order ...............
 
S

srnet

Senior Member
MFB said:
Maybe an antenna mounted Ramsey LNA will at least help overcome cable/connector losses?
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Sure will, cable loss can be significant at these frequencies.

Unless you using the real expensive low loss stuff at a mere £3-£5 per metre.
 
S

srnet

Senior Member
MFB said:
Oh! I have just receive a Ramsey LNA that I planned to use with my Baofeng and this type of antenna...
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And that is a good antenna to try, simple build.

You will find that even a simple antenna like the Moxon (or BiQuad) will improve reception more than even £sssss of low noise amplifier.
 
S

srnet

Senior Member
Another contender in the good gain but simple to build antennas for 70cm.

The Moxon;

http://www.moxonantennaproject.com/2E0RHM/2E0RHM.htm

I built one and listened out this morning, $50SAT's closest approach was 1063km. Beacon clearly heard with FT60 handheld and no LNA.

I also heard it at 12:11:30, weak but clear enough. I checked Orbitron and $50SAT would have been at 1700km, so promising.

Over the park to test, and it produces 2.5dB more signal than the BiQuad, so somewhere around 8dB gain.
 

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M

MFB

Senior Member
srnet said:
Another contender in the good gain but simple to build antennas for 70cm.

The Moxon;

http://www.moxonantennaproject.com/2E0RHM/2E0RHM.htm

I built one and listened out this morning, $50SAT's closest approach was 1063km. Beacon clearly heard with FT60 handheld and no LNA.

I also heard it at 12:11:30, weak but clear enough. I checked Orbitron and $50SAT would have been at 1700km, so promising.

Over the park to test, and it produces 2.5dB more signal than the BiQuad, so somewhere around 8dB gain.
Click to expand...
Hello,

Thanks for the feedback on the Moxon antenna. As I mentioned before, the plan was to use this type of antenna with a LNA. However, following your encouraging test results I'll try mounted directly to the receiver but still think it may be worth adding the LNA if longer cable runs are required.

Do you have any plans to publish a reference design for a $50SAT ground station that incorporates all your experience with rf and decoding software?
 
S

srnet

Senior Member
MFB said:
Do you have any plans to publish a reference design for a $50SAT ground station that incorporates all your experience with rf and decoding software?
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No, as the necessary details of how to decodes the various modes were published in the communications document (on the dropbox) at the time of launch.
 
S

srnet

Senior Member
It does not get much easier or cheaper than this, cheap Baofeng UHF, some wire, a socket, a bit of plastic and tape + 30minutes of time.

There is a recording here;

https://www.dropbox.com/sh/l3919wtfiywk2gf/TjpVrYgPZD/Pass Information

Called;

300114 - Baofeng and Moxon at 1800km.wav

Recorded this morning, its the Morse beacon from $50SAT when it was 1800km away, you will hear the Morse, and towards the end the sound the data packets make.
 

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S

srnet

Senior Member
MFB said:
Really neat solution but that coupling looks rather lossy.
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But not too lossy, it would seem, 1800km.

Its a compromise, as a lot of these things are, reduce the spacing with fewer connectors and you hand detunes the driven element.

Putting it on cable, see previouis post, stope your body detuning it, and there is less loss.
 
G

Goeytex

Senior Member
I recently made a Gray-Hoverman Antenna from plans on the Internet. This homebuilt easily outperformed a Radioshack YAGI. While dimensions are for US HDTV band, it could be tuned for $50SAT.
 
P

Paix

Senior Member
@Eclectic, I see a download page with links, the second link was the pass recording with a file date/time around mid day Thursday 30 January 2014.

Assuming that you have been able to see Srnet's Drop box page previously, you shouldn't be having any problems?

@Srnet I hear the "AB2S" and something muffled then just noise until the end of the file. Was that the complete pass capture, or an edited excerpt of the best in the pass?
 
E

eclectic

Moderator
Paix said:
@Eclectic, I see a download page with links, the second link was the pass recording with a file date/time around mid day Thursday 30 January 2014.

Assuming that you have been able to see Srnet's Drop box page previously, you shouldn't be having any problems?
Click to expand...
I heard it at ~15.10
See my edited addition post #20

And, while I'm here,

what's the (approximate) attenuation factor
for double glazed windows?

(Brits will appreciate the reason for wishing to stay inside).

e
 
S

srnet

Senior Member
Paix said:
@Srnet I hear the "AB2S" and something muffled then just noise until the end of the file. Was that the complete pass capture, or an edited excerpt of the best in the pass?
Click to expand...
I only recorded the last bit of the pass, although $50SAT is then a lot further away, directing the antenna is not so critical, so you can get a better recording that way.

Right at the end of the recording you can hear the noise the packets make.
 
P

Paix

Senior Member
@Srnet, thanks on that. The CW was at a good level and a nice speed, around 16WPM at a guess.

@Eclectic, especially if you live anywhere near the Somerset levels. Not sure if that is shallow level or not!
It depends on your particular double glazed unit construction and perhaps the use of Pilkington K glass.

"The benefits of reduced condensation and high thermal insulation obtained from using Pilkington K Glass&#8482; are due to the presence of a special transparent metallic type coating on one of the surfaces of the double glazing unit. This ultra-thin coating is transparent but has a very small effect on white light transmission.

Pilkington K Glass&#8482; has high light transmission and often appears indistinguishable from clear float glass. For this reason it is recommended that the presence of the coating is confirmed by the use of a Pilkington K Glass&#8482; detector after installation. However, the coating does have a pale straw coloured tint and when a light coloured object or material is viewed through the glazing, depending on local circumstances and conditions, occasionally a slight darkening effect may be seen. "

You aren't living in a Faraday cage are you e? Obviously don't have the wife outside pointing an antenna for you then! :)
 
E

eclectic

Moderator
Cheers Ian. :)

In the last few days, I've built

A quadrifilar

A Moxon

A Bi-quad (but as a double-circle "spectacle" shape)

All work very well (behind glass)
with local amateurs on 70cm.

However, at 600 - 2000 km and flea-power Tx,
the glazing is the last Chance for the signal.
(Feeble attempt at glass pun).

e
 
P

Paix

Senior Member
I should build a Moxon and a Bi-quad, but other things have been occupying a lot of my time of recent.

Regular skeds 144.330MHz 2100 - 2200 USB (vertically polarised) Monday & Thursdays ( G0PAI and M0LIT regulars subjects Picaxe, Arduino, Raspi, life, bees, gizmos from China etc.)
433.550MHz 2100 - 2200 FM Tuesdays, same cast same subject areas.
Give a little listen and call if you hear us.
 
M

manuka

Senior Member
Rev. Ed's Clive has a "PICAXE in Space" article in the Feb. 2014 Silicon Chip mag. I'll post a screen grab if folks are interested. Stan
 
S

srnet

Senior Member
I have started to build a demonstration model of $50SAT, a picture of the bare chassis is attached, it really is just bits of aluminum sheet and angle.

This will be great for presentations, perhaps the first time a real live satellite that people can pick up and handle.

Good job they are so cheap to make, doubt anyone would be happy handing round a £Thousands Cubesat.
 

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M

MFB

Senior Member
It would be nice to see this article and Rev-Ed have missed a trick if they are not able to include a copy on their web site.
 
S

srnet

Senior Member
The $50sat team is celebrating 90 days in orbit by proposing a technical challenge to all interested amateurs. $50sat is capable of responding to uplink command packets:

There are 3 open packets:

Test packet - $50SAT responds by sending the RSSI of the received packet in slow FM Morse.

Request data packet - the normal data packet is sent.

Request RTTY - The RTTY is sent.

In addition all received packets result in two copies of the ack packet being sent, that contains the RSSI of the received packet.

All the required information to accomplish this is available on the drop box location available
through the $50sat web page at www.50dollarsat.info .

Anyone that can demonstrate a successful command uplink by submitting a recording of the response packet along with the date, time and location of of the contact will receive a Certificate of Technical Accomplishment signed by all three builders of $50sat. Submissions can be made to the $50sat email address; 50dollarsat at yahoo.com. This is a significant challenge because there is no magic black box that you can buy to do this.

After 90 days of operation, the Kodak KLIC-7002 camera battery that powers the satellite has fallen off about 100mV, but operations still seem normal.

We have also programmed a special 5th morse beacon to thank our launch sponsor and mentor prof. Bob Twiggs. Please give a listen for the message TNX KE6QMD on the FM Morse beacon.

QSL cards are still available to anyone that posts telemetry, either hand copied CW or RTTY captures, to the 50dollarsat yahoo group.

73 and good luck to all from the $50sat team
 
S

srnet

Senior Member
I have at least one presentation to do on $50SAT, so I could do with an unclutered easy to read schematic.

So I took the original circuit diagram from Eagle and removed all the bits and options that were not actually used.

Attached is a pdf of the processor\radio schematic, as $50SAT is now.

Not a lot too it really.
 

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