Replacement RF module for Eggfinder

[amiliv]

Looks like I somehow managed to fry RF module for the Eggfinder while soldering it to the LCD receiver board. After heroic fight, I managed to unsolder it and not ruin the main board in the process. Used RF module from unassembled tracker as spare, and voila the receiver now works...

But alas, now I'm short one RF module for the said tracker. From the markings this seems to be HM-TRP-915. I can't find this part at standard places like DigiKey and Mouser. There seems to be a bunch on eBay like this one https://www.ebay.com/itm/143439411663. Is that the part? Yup, I'll be careful to get 915MHz version. I'd hate to get wrong part then have to spend an hour unsoldering it.

I've seen some of these sold as HM-TRP-915, and some sold as HM-TRP-915S. Same thing?

Yes, I'd normally ask Cris, but have trouble reaching him for the past few days.

 

[cerving]

Don't get the ones from eBay, they almost always have 3DR firmware burned into them and will not work with Eggfinders (which use the original factory firmware). I think you got this resolved, correct?

 

[amiliv]

Don't get the ones from eBay, they almost always have 3DR firmware burned into them and will not work with Eggfinders (which use the original factory firmware). I think you got this resolved, correct?

Hi Cris. Yup, I got receiver resolved, just need the RF module for the extra transmitter I bought. Where would you recommend to get them? I also found this page, but with shipping it'd end up over $20 https://www.tme.com/us/en-us/details/hm-trp-915s/rf-modules/hope-microelectronics/?brutto=1.

 

[cerving]

Normally we sell them separately as replacement parts, they're $10. However, I don't have any to spare... there is a shortage of the RF modules, due to a fire in a wafer-producing factory in Japan that makes the silicon wafers for the company that makes the key chip in the RF module. My supplier (the factory-authorized distributor, BTW) is quoting 4-6 weeks, so it may be awhile. Sorry... unfortunately, component shortages have become a fact of life recently (see the PF SLCF thread as an example...)

 

[amiliv]

If I got it right from the web, 3DR firmware is popular with RC airplane people? I found some websites that explicitly say the one they sell has 3DR firmware, so those won't work... And many, including TPE, that don't say anything about which firmware it has (so I'd be getting a cat in a bag).

Aliexpress (as much as I'm not fan of it and it's parent company) seems to be the only one I was able to find that offers both "standard" and "3DR" firmware options explicitly (this one). So, my options are either that, or getting on the waitlist for when you get next shipment (in month or two, I guess?).

 

[cerving]

If I got it right from the web, 3DR firmware is popular with RC airplane people? I found some websites that explicitly say the one they sell has 3DR firmware, so those won't work... And many, including TPE, that don't say anything about which firmware it has (so I'd be getting a cat in a bag).

Aliexpress (as much as I'm not fan of it and it's parent company) seems to be the only one I was able to find that offers both "standard" and "3DR" firmware options explicitly (this one). So, my options are either that, or getting on the waitlist for when you get next shipment (in month or two, I guess?).

Any time you see "APM flight control" you can pretty much assume that it's using 3DR firmware. They may not have them either... the shortage is due to the SI1000 chips on the RF module (which are used by a lot of other RF devices, too). That Renesas fire is going to have some pretty far-reaching global consequences... they're a big supplier to the automotive industry.

 

[Apogee4234]

I am sorry about this post. Because I did not found how can post in new topics.

We try to send photo in 433MHz frequency(In a Rocket competition in TURKEY) but we need to Data rate for calculate "In 6000 meter could we send photo, how much time ?" . I reach this calculation(BUT THIS USE IN FSK MODULATION). But there is a problem that we use OOK modulation. WE CAN NOT USE THIS CALCULATION. We need help about data rate calculation in OOK modulation. We got lost data when change the SF value like SF:7 to SF:12. I am new about LoRA devices. We use RFM98PW (in transmitter side) and RFM98W(in receiver side). Also, we use Yagi antenna in receiver side and 433MHz RF antenna in Rocket. In additon, we use ESP32-CAM for take photo in Payload of rocket(Like a satellite).

My second question, Is bandwith important factor on OOK modulation?

Calculation for FSK modulation:
DRata Rate
SF: Spreading Factor
CR: Coding

DR = SF x BW / 2^SF x CR
If anyone recommend any calculation about OOK modulation that I will really appreciated .


You can see the Datasheets:

RFM98PW(In transmitter side)
https://pdf1.alldatasheet.com/datasheet-pdf/view/1139154/HOPE/RFM98PW-433S2.html
RFM98W(In Receiver Side)
https://pdf1.alldatasheet.com/datasheet-pdf/view/750175/ETC2/RFM98W-433S2.html
ESP32-CAM(In payload, take photo)
https://media.digikey.com/pdf/Data Sheets/DFRobot PDFs/DFR0602_Web.pdf

 

[cerving]

In OOK, you just need enough bandwidth from the carrier frequency to cover the modulation frequency, so typically a few KHz will do. That's why CW will cover much longer distances than voice or digital, the "data" rate is low so the SNR is higher. You're not going to be able to use OOK with video, however, you're probably going to have to either use an analog transmission or some kind of digital scheme, probably with data compression. The EU regulations for license-free bands aren't very amenable to video transmission... most of the bands have either pretty severe power limitations (10 mW or less) or they have low duty cycle limitations (typically 10% or less). If you have somebody on your team with an amateur radio (Ham) license, the 433 MHz band would probably be your best bet, otherwise you'll be looking at the "worldwide" bands... 2.4 GHz and 5.8 GHz. Good luck... sending real-time video from a rocket isn't easy, even with "packaged" solutions.

 

[Apogee4234]

Thanks buddy, We will not sent video in real-time. We just try to send photo in 10-15 second. How can we learn which bandwith suitable for us? (433MHz and OOK modulation)

 

[Apogee4234]

Additonally, we use this library :

https://github.com/SMotlaq/LoRa

 

[cerving]

LoRa is designed for long-range low-bandwidth communications, it's fine for telemetry and GPS data but it's unlikely that you'll be able to send a photo with it (even compressed they're typically several hundred Kbytes). I'm not sure there's any point in sending a picture every 10-15 seconds from your rocket... you won't get much worth looking at. You're better off just having the video stream to a flash memory card and viewing/processing it on the ground.