I'm currently building a satellite type project and I am looking for a low power way to send photos with a CC1101 transmitter and any sort of camera attached to an arduino, I can't seem to find how to do it with SSTV but are there any other ways to do this? Thanks!
Julianfer5:
I'm currently building a satellite type project and I am looking for a low power way to send photos with a CC1101 transmitter and any sort of camera attached to an arduino, I can't seem to find how to do it with SSTV but are there any other ways to do this? Thanks!
So your planning to put a CC1101 transmitter into orbit around the Earth ?
Tell us more.
Convert the image into data bytes and send those at a low data rate, using any radio (including the CC1101).
srnet:
So your planning to put a CC1101 transmitter into orbit around the Earth ?Tell us more.
Well I thought of the cc1101 since it has flight heritage on other space missions, any other transmitter suggestions? Im trying to make the smallest possible satellite/ data transmission device at the lowest possible price with consumer parts, currently have a working smd 3x3cm model with an HCM5883l, MPU6050 and BMP180 transmitting with a 433mhz transmitter and a 3x3cm solar panel. Now I am trying to add range with a new transmitter and photo functionality.
jremington:
Convert the image into data bytes and send those at a low data rate, using any radio (including the CC1101).
Any easy way to do this? I have pretty basic coding knowledge and can sorta get around and do collages.
Thanks!
First pick a camera that can transmit an image over a serial connection, keeping in mind that the standard Arduinos have far too little memory for image storage or manipulation.
jremington:
First pick a camera that can transmit an image over a serial connection, keeping in mind that the standard Arduinos have far too little memory for image storage or manipulation.
I believe I have an Arducam OV2640 modules laying around, Could this work?
If this is from orbit then you need to sort out how your going to get any digital data back at all, let alone enough for a picture, then work out how your going to provide the power.
Data reception from small FSK modules in orbit is highly marginal, due in part to the power limitations that small satellites impose, typically 100mW max and for very short periods.
Small satellites is a numbers game, you can only do what the numbers allow.
Can you provide examples of where the cc1101 has been used on other space missions ?
The kicksat and Aerocube-4 used the CC1101 as transmitters, Looking back at this now the main idea really is not to have a camera and I was just thinking of it as an addon. The transmission power and power consumption of a camera is something to complicated for a satellite of this size. However, I am looking to implement the CC1101 or similar in the satellite for sensor data transmission. Any easy libraries for sending data with this tx? thanks.
Julianfer5:
The kicksat and Aerocube-4 used the CC1101 as transmitters, Looking back at this now the main idea really is not to have a camera and I was just thinking of it as an addon. The transmission power and power consumption of a camera is something to complicated for a satellite of this size. However, I am looking to implement the CC1101 or similar in the satellite for sensor data transmission. Any easy libraries for sending data with this tx? thanks.
There are libraries for the CC1101, just try a Google search on 'Arduino CC1101'
I guess if your doing a Cubesat then there is likley the power available to drive the device at 1W power output, the extra 10dB link gain over 100mW makes all the difference.
The obvious modern device would be a LoRa module, assuming you can get an experimental amateur licence to use the devices spread spectrum. These devices would have a range improvement over the CC1101 of around 10 or more times.
Ah ok, It's not actually a cubesat but a much smaller board based picosatellite at around 2x2x0.3cm. I was indeed looking at LoRa devices too, something like the RFM95/RFM95W but I am currently unable to get an amateur license in Spain and they are over the power budget unless I can design some sort of short-term capacitor for short high power transmissions.
Thank you so much for your help,
Really aprecciated!
Julianfer5:
Ah ok, It's not actually a cubesat but a much smaller board based picosatellite at around 2x2x0.3cm. I was indeed looking at LoRa devices too, something like the RFM95/RFM95W but I am currently unable to get an amateur license in Spain and they are over the power budget unless I can design some sort of short-term capacitor for short high power transmissions.
@434Mhz if you slowed LoRa down to 150bps, you would likely get 1000km @ a mere 10mW.
Actually, for the low amount of data I am sending, I think that would work fine. There's about 80mw of constant power for the transmitter as is.
Also, quick question, are the antennas supposed to be opened up a certain time after launch or can they just be spring mounted to open up after being ejected? Thanks!
Julianfer5:
Actually, for the low amount of data I am sending, I think that would work fine. There's about 80mw of constant power for the transmitter as is.
Also, quick question, are the antennas supposed to be opened up a certain time after launch or can they just be spring mounted to open up after being ejected? Thanks!
That would rather depend on the launch method.
$50SAT took the ultra simple approach, we used steel tape rule which was folded back down the lenngth of the satellite inside the launch tube. So the antenna deployed as soon as it was pushed out, but that was only possible because of the method of launch.
srnet:
That would rather depend on the launch method.$50SAT took the ultra simple approach, we used steel tape rule which was folded back down the lenngth of the satellite inside the launch tube. So the antenna deployed as soon as it was pushed out, but that was only possible because of the method of launch.
Ah ok, Did GAUSS allow you to have the satellite on during launch or did you have to use some sort of timer until it started transmitting?
Thanks
Battery had to be disconnected during launch. Two microswitches connected the battery when it was ejected out of the launch tube. It started transmitting immediatly.
I also did the software for a beacon that was launched from the ISS a few months back, that had to wait for two days before starting transmitting.
srnet:
Battery had to be disconnected during launch. Two microswitches connected the battery when it was ejected out of the launch tube. It started transmitting immediatly.I also did the software for a beacon that was launched from the ISS a few months back, that had to wait for two days before starting transmitting.
That is a great idea haha, so simple yet so effective, Damn amazing stuff man!. Last question hahaha, Is active attitude control worth it on a pocketqube? Can you use everyday neodymium magnets for passive control? Thanks!
Julianfer5:
That is a great idea haha, so simple yet so effective. Last question hahaha, Is active attitude control worth it on a pocketqube? Can you use everyday neodymium magnets for passive control?
Active control would be hard, remember the power constraints caused by the low surface area available for solar panels. The more stuff you add ther more there is to go wrong.
We used a single neodymium magnet which worked well. In retrospect it should have been at a different angle so that the solar panels spent more time fully pointing at the sun. A second magnet, also realised in retrospect, would probably have stopepd it spinning along its long axis. The spinning caused the FSK RTTY to fade in and out a bit.
Its easy to dismiss the FSK RTTY we used as old tech, but it was the main reason for the projects sucess. The advantage was that virtually every radio amateur in the World listening on 434mhz had the gear to pick up the basic telemetry. As a result we had a great many reception reports from all corners of the World. Even at 2000km+ I was able to pick up the data sent at 100mW using a simple omni antenna.
I did write Arduino FSK RTTY software for the LoRa devices.
srnet:
Active control would be hard, remember the power constraints caused by the low surface area available for solar panels. The more stuff you add ther more there is to go wrong.We used a single neodymium magnet which worked well. In retrospect it should have been at a different angle so that the solar panels spent more time fully pointing at the sun. A second magnet, also realised in retrospect, would probably have stopepd it spinning along its long axis. The spinning caused the FSK RTTY to fade in and out a bit.
Its easy to dismiss the FSK RTTY we used as old tech, but it was the main reason for the projects sucess. The advantage was that virtually every radio amateur in the World listening on 434mhz had the gear to pick up the basic telemetry. As a result we had a great many reception reports from all corners of the World. Even at 2000km+ I was able to pick up the data sent at 100mW using a simple omni antenna.
I did write Arduino FSK RTTY software for the LoRa devices.
Yeah I was thinking indeed attitude control would be too demanding for the power capabilities of a picosatellite that size, I am actually contemplating the idea of possibly keeping the voice synthesizer meaning anyone can tune in without decoding, maybe some sort of alternation between coded audio and synthesized voice. Did you take any action to counteract the doppler effect?
Thank you so much man!
Julianfer5:
I am actually contemplating the idea of possibly keeping the voice synthesizer meaning anyone can tune in without decoding, maybe some sort of alternation between coded audio and synthesized voice.
Voice ?
You sure, have you actually tested that you will have enough link margin that it will be heard ?
Did you take any action to counteract the doppler effect?
It would in theory be possible to adjust the frequency of transmissions to compensate for ground reception, but it could only be done for one particular point on the globe, or if you had two way comms with the satellite to instigate the 'compensation' when required.
But to answer the question then no, we did not take any action to compensate for doppler, basically because its not really possible in such simple systems. I did (extensivly) test that the ground based recievers could cope with the known frequency shifts due to doppler.
srnet:
Voice ?You sure, have you actually tested that you will have enough link margin that it will be heard ?
It would in theory be possible to adjust the frequency of transmissions to compensate for ground reception, but it could only be done for one particular point on the globe, or if you had two way comms with the satellite to instigate the 'compensation' when required.
But to answer the question then no, we did not take any action to compensate for doppler, basically because its not really possible in such simple systems. I did (extensivly) test that the ground based recievers could cope with the known frequency shifts due to doppler.
I have not tested anything yet but will start testing soon hopefully, voice could be an interesting addition to the amateur ham community even though RTTY decoding is dead easy with an SDR nowadays. Yeah I thought doppler effect would be hard to counteract at such a basic RTTY transmission it would not have much effect.
Anyways I'll start experimenting with a couple LoRa radios I have ordered and will keep you updated, But pretty much its a basic PocketQube possibly acting as a mothership to launch the smaller picosatellites.
Thanks Man your help is really helpful and the work you did and are doing is amazing!
Cheers,
Julian