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Telemetry with an APRS-like system

Bubblehead

Bubblehead

Well Known Member
So it's been 26 years since I took my Advanced Class test (and passed) and have renewed the license at the right time so am still legal. KC9PR. The new cylinders I put on the RV-8 are breaking in nicely and the EIS 4000 is working fine and is completely programmed, so it is time for another project.

I ordered a Micro-Trak 8000 last winter and have had it sitting on my workbench for the last month to get me motivated. Recently I read some posts somewhere about people thinking about using telemetry systems especially during test flights or while evaluating engine or airframe changes. I doubt 2M band, especially the APRS frequency, is the right or legal place to do it, but why couldn't the same type of system be used to send the serial output data generated by the EIS 4000 to a ground station? Perhaps it would not need to be a continuous data stream, just a data dump every minute or few minutes.

Like I said above, I've been out of the amature radio scene for a long time, but I'm sure Sam or some of the other radio heads out there could come up with a simple system like APRS for telemetry. Heck, it's probably been done already I just have not heard about it.

Any ideas?
 
EIS 4000

Do you have any idea of what the data coming out of the EIS 4000 looks like? If you can point me to a spec, we might be able to encode the data as ax.25 APRS data.

Best regards,

Allen
VHS
 
You might be able to figure it out at this website:

http://iflyez.com/EFISRecorder.shtml

There is a manual and software (free) on the site. Perhaps the data blocks are defined in those.

Here's a link to a site with a GRT decoding utility program. Since this was written by a RVer he might be on these forums.

http://www.rvproject.gen.nz/grt/

One more possible source is www.eismate.com.

I am currently buying a license for his software. He seems like a very nice man and he might share that info. Let me know if you can't get it any other way and I'll email EISMate. His software makes a Palm T2 into a graphic display for the EIS 4000.

Hope it helps.
 
Model 4000/6000 Serial Data List

Code: 
Model 4000/6000 Serial Data List

All data is transmitted at 9600 baud, one stop bit, no parity. The first 3 bytes are a header that is unique, and will not show up in the data stream.

All 2 byte data is listed with an "H" and an "L" following the name of the data.  To combine these two bytes into the result, multiply the high word by 256 and add the low word to the result.

All data is scaled with the least significant bit = 1 unless noted. All data is unsigned unless noted.

$FE        ; Header word #1 (Decimal 254)
$FF        ; Header word #2 (Decimal 255)
$FE        ; Header word #3 (Decimal 254)
TACHH      ; Tachometer - Resolution = 1
TACHL
CHT1H      ; CHT and EGT follow all have
CHT1L      ; a resolution of 1 deg
CHT2H
CHT2L
CHT3H
CHT3L
CHT4H
CHT4L
CHT5H
CHT5L
CHT6H
CHT6L
EGT1H
EGT1L
EGT2H
EGT2L
EGT3H
EGT3L
EGT4H
EGT4L
EGT5H
EGT5L
EGT6H
EGT6L
DAUX1H      ; Reserved
DAUX1L      ; Reserved
DAUX2H      ; Reserved
DAUX2L      ; Reserved
ASPDH       ; Airspeed
ASPDL       ;
ALTH        ; Alitiude in feet
ALTL
VOLTH       ; resolution of 0.1 Volts
VOLTL
FUELFH      ; Fuel Flow (Gallons/Hour) resolution of 0.1 gallons/hour
FUELFL      ;
UNIT        ; Internal Insturment temperature
CARB        ; 2's compliment
ROCSGN      ; Vertical speed - 100 fpm resolution 2's compliment
OATH        ; 2's compliment - there is no low word
OILTH       ; Oil Temperature
OILTL
OILP
AUX1H       ; Auxiliary 1
AUX1L
AUX2H       ; Auxiliary 2
AUX2L
AUX3H       ; Auxiliary 3
AUX3L
AUX4H       ; Auxiliary 4
AUX4L
COOLH       ; Coolant Temperature
COOLL
ETIH        ; Hourmeter - Resolution = 0.1 hours
ETIL        ;
QTYH        ; Fuel Quantity (fuel flow totalizer) Resolution = 0.1 gallons
QTYL
HRS         ; Flight timer hours
MIN         ; Flight timer seconds
SEC         ; Flight timer seconds
ENDHRS      ; Fuel FLow time until empty - Hours
ENDMIN      ; Fuel FLow time until empty - Minutes
BAROH       ; Baroset in In HG - Resolution 0.01
BAROL       ;
MAGHDH      ; Magnetic Heading - Hi word
MAGHDL      ; Magnetic Heading - Lo word -resolution 0.1 degrees
SPARE       ; Reserved.

Checksum (data summed and result complimented) is transmit here - 1 word. The checksum
does not include the header, but does include the "SPARE" word. The checksum is a single, 
8-bit word.
If anyone is interested, I've got very crude perl and python scripts that can swallow the continuous serial data stream, grab records at specified intervals (the are about 11 records a second, but you probably don't really need that many) decode the records, add a time stamp to each record, and write it to a computer disk.
 
Thanks, Kevin

I should have known you'd have the info. Perhaps now VHS or Sam or some other RVer/Ham will run with this idea.
 
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