Introducing the Eggtimer Telemetry Module

[cerving]

Eggtimer Rocketry is proud to introduce the Eggtimer Telemetry Module, an add-on for your Eggtimer Quark, Quantum, or Proton altimeters. The Eggtimer Telemetry Module (ETM) transmits real-time data from your Eggtimer Altimeter to an Eggfinder LCD receiver, giving you real-time visibility into what your rocket is doing, and also some important "historical" data. Real-Time data may include current altitude, velocity, acceleration, elapsed time, deployment channel status, voltage, and temperature (device dependent). Historical data may include apogee, maximum velocity, and maximum acceleration. Have you ever had a rocket go out of sight and wondered how high it was, or if the deployment channels fired, or how fast it was coming down? Well, now you'll know!

The ETM connects to your Quark, Quantum, or Proton with a simple 3-wire cable using socket pins; you don't have to solder it in permanently. It gets its power from the altimeter, so no separate battery is required. Current draw is about 27 mA typical. It's about 40mm x 18mm, the wire antenna adds about 80mm; weight with the wire antenna and cable is about 10 grams. You'll need to update your Quantum or Proton to the current firmware version to support the ETM, as well as your LCD receiver; the firmware is already on the web site (Quantum 1.08K, Proton 1.04L, and LCD 2.01c).

Data is transmitted to an Eggfinder LCD receiver, it's the same one that's used for our GPS transmitters, however you can't receive and decode both data streams at the same time (you don't really want to interrupt your GPS data anyway, do you?) If you have an extra one, you only need the ETM to get started; we're also going to be selling packages with both the ETM and the LCD receiver at a discount (just like we do for the GPS transmitters).

We will be offering ETM's in the same bands that we do for our GPS products... 900 MHz US/Canada, 900 MHz AUS/NZ, 869 MHz EU/UK, and 70cm Ham.

Price for the ETM transmitter is $20, the 70cm Ham version is $30 (it's more because it includes an external antenna). Packages with an ETM and LCD receiver start at $70, even less if you don't need the case/hardware package.

You can read all about it on our web site, EggtimerRocketry.com. Availability will be approximately May 20th, 2021 (boards are due in on the 17th).

As usual, thanks for your continued support!

Cris Erving, Eggtimer Rocketry

 

[rharshberger]

Ohh.....!

 

[SecondRow]

I was wondering how my lcd receiver was going to pick up both the gps and telemetry data.

Just gonna earmark the money now…

 

[Kelly]

This is uncanny; just in the last week I've been investigating modules I could use to grab serial data from my eggtimers and beam back to me. This is much better since it uses the LCD I already have.

Question - since this doesn't seem to work well with the TRS (requires two separate LCD receivers, and room for two transmit antennas on the rocket) is there any way the TRS firmware can be updated to provide velocity data on the LCD?

 

[cerving]

The TRS already transmits "some" telemetry to the LCD receiver (altitude, channel status). The format is different, however, so it can't be decoded with the ETM data routines. We've thought about adding velocity to the TRS' data, unfortunately there isn't enough space in the program flash memory to add it.

 

[Charles_McG]

Will the dongle receiver work with the ETM?

 

[cerving]

Yes, but you'll have to decode the data yourself since all you'll get is the raw data. If you want to write a program to do that, it shouldn't be too hard... and you can make a pretty GUI out of it, too. I don't have the time to do it myself, however the data format will be posted if somebody wants to take a crack at it. It's all readable ASCII text... no fancy packed binary, CRC's, or anything like that.

 

[dvdsnyd]

The TRS already transmits "some" telemetry to the LCD receiver (altitude, channel status). The format is different, however, so it can't be decoded with the ETM data routines. We've thought about adding velocity to the TRS' data, unfortunately there isn't enough space in the program flash memory to add it.

Have you looked into changing micros or having some extra external flash on the board?
Seems you are just about tapped out.
I'm pretty excited about this, going to have to pick one up Nice work Cris!

 

[cerving]

Yes, I have looked at refreshing the TRS... have not seen anything I liked yet. The biggest issue is that all of the candidate processors are quad-packs, so I'd have to pre-mount them like the baro chip, and it would be difficult to pre-program them.

 

[cerving]

I've had a few people ask me what it looks like in an AV bay. This is a 54mm AV bay with a Proton and an ETM... these are prototype boards so they're not quite the same as the production boards, but you should get the gist of it.

 

[heada]

Looks like you have the pads for using an RP-SMA instead of the wire. Is that correct?

 

[dvdsnyd]

I've had a few people ask me what it looks like in an AV bay. This is a 54mm AV bay with a Proton and an ETM... these are prototype boards so they're not quite the same as the production boards, but you should get the gist of it.

HEEEEEYYY!!! Is that all thread running through that bay?!
Another case of do as I say, not as I do....

Looks really nice Cris! I wouldn't have thought about running it like that.
As always, great work!
Dave

 

[dvdsnyd]

Yes, I have looked at refreshing the TRS... have not seen anything I liked yet. The biggest issue is that all of the candidate processors are quad-packs, so I'd have to pre-mount them like the baro chip, and it would be difficult to pre-program them.

That's a bummer. I hope you can find something. I can't imagine what you would be able to do with some more program room!

 

[cerving]

HEEEEEYYY!!! Is that all thread running through that bay?!
Another case of do as I say, not as I do....

Dave

There's no getting around the fact that if you have a transmitter in the AV bay the RF setup is not going to be optimal. When I get a laptop to replace the one that blew out a power supply a few days ago, I'll be able to post the docs... there's a discussion of this in the User's Guide. The bottom line is that for most purposes it's "good enough"... you WILL lose some transmissions, however the ETM event data is repeated with every transmission, so you might not get a deployment confirmation the first transmission after it happens but you'll get it a few seconds afterwards. I've flown up to 14K so far with motors from longburns up to whomp motors, and the data transmission pattern is pretty consistent. You can run an antenna outside the AV bay, too... I have not tried that yet, I was more concerned with making sure that there was good data being displayed on the LCD receiver if the transmissions were intermittent.

 

[dvdsnyd]

There's no getting around the fact that if you have a transmitter in the AV bay the RF setup is not going to be optimal. When I get a laptop to replace the one that blew out a power supply a few days ago, I'll be able to post the docs... there's a discussion of this in the User's Guide. The bottom line is that for most purposes it's "good enough"... you WILL lose some transmissions, however the ETM event data is repeated with every transmission, so you might not get a deployment confirmation the first transmission after it happens but you'll get it a few seconds afterwards. I've flown up to 14K so far with motors from longburns up to whomp motors, and the data transmission pattern is pretty consistent. You can run an antenna outside the AV bay, too... I have not tried that yet, I was more concerned with making sure that there was good data being displayed on the LCD receiver if the transmissions were intermittent.

Thanks for the great explanation Cris. I was poking fun, and didn't mean anything mean by it. What you are saying makes perfect sense. Bummer about the laptop. I look forward to the discussion in the user guide!
Thanks again,
Dave

 

[John Kemker]

Me likey. Me want.

 

[cwbullet]

Nice addition to the product line.

 

[jbrracer]

Cris couple easy questions,

with the lcd update with it still work correctly with the TRS and trackers? Or do I need a separate lcd?

with the proton does it display all six channel statuses?

 

[cerving]

The LCD update is for both the GPS trackers and the ETM. One nice feature is that if you DON'T have a TRS, you can tell the LCD to ignore the 45-second "Waiting for Sync" period that's used for TRS pairing.

The LCD receiver can only decode one type of data stream at a time, so if you're running an Eggfinder GPS transmitter (or TRS) and an ETM, you'll need a separate LCD receiver for each one, on separate frequency/ID's. If you put them on the same frequency/ID accidentally, you won't get telemetry, but you'll still get the GPS data. Like the GPS's, I expect most people to pick a (non-default!) frequency/ID combination, and use that for all of their transmitters; the ETM is frequency/ID programmed just like the TX and the Mini, except that you don't use a separate pairing cable, you use the data cable that attaches to the altimeter.

The ETM deployment status data shows all outputs, and whether they are enabled, disabled, or have been fired. When I get my replacement laptop I'll finish up the docs and post them... hopefully Monday night.

 

[GrouchoDuke]

Huge congrats on getting this out. Good stuff!

 

[cerving]

So, I got my replacement laptop yesterday, spent the rest of the day setting it up and getting the data from the old drive loaded onto it, and we're back to normal. I have uploaded the Eggtimer Telemetry Module Assembly and Users Guide to the web site, you can find it under Support/Eggtimer Telemetry Module. Thanks for your patience... I know that a few of you have received your ETM kits already, now you'll know what to do with it.

 

[cerving]

I've also posted the data specifications, I've had a few people ask about that. It's a very simple ASCII protocol... it had to be simple to work with a Quark.

 

[user 30299]

Received this fine package the other day. There's a gentleman just 35 miles from my house that does a great job of assembling these kits. Our high-altitude field just shut down for the planting season, so I may have to wait a few months to give the new module a high-altitude test, bummer.

 

[n27sb]

Just assembled the first telemetry module. As per Cris's new guide, everything linked right up and worked.