Using RTLAMR.exe to capture data from Itron ERT Gas Meter 100G DLN

[rohitjindal786]

@bemasher please guide
I am new to this ERT Technology. We have a requirement to capture the data of Itron's the ERT Gas meter 100g DLN using CC1111 Usb dongle from Texas Instruments.

CC1111 transceiver Usb dongle : from TI capture some fix formatted packets under frequency ranges from 868/915 specifically ISM Bands, using some good tools provided like Smart RF Packet Sniffer, Smart RF Studio by TI. (datasheet
https://www.ti.com/lit/gpn/cc1110-cc1111).
CC1111 understanding :
1 Fixed packets i want to highlight the packets format being defined by Texas for the dongle . We can set the how many byte preamble of packet will be that can be 2 byte /3/4/5 bytes but we cant set what will be its value.
2 We can just set 16bit SYNC0/SYNC1 sync word but we cant set that packets 30/32 bit sync word but we can declare that packet can have 30/32 bit sync word but there is option to set only 16bit sync word.

ERT:
1 Regarding ERT protocol what we have is just this Wiki page https://en.wikipedia.org/wiki/Encoder_receiver_transmitter so we are not actually 100% sure of how ERT actually works.
2 Wiki has mentioned that ERT works on OOK modulation but i could not find similar in RTLAMR Source code by Bemasher.
3 Wiki has mentioned that ERT support Manchester coding but similar i could not found in RTLAMR source code.

From last 2 months we are trying to capture the gas meter data using CC1111 dongle but we did not succeed anyhow.

Testing:
Using Bemasher/rtlamr : we purchased a dongle DVB-T+DAB+FM"" RTL2832 based DVB-T recievers,
we run rtl_tcp.exe that uses the dongle to start listening for data being set on particular frequency under ISM Range say 912600155.
On other end we are running rtlamr.exe that finally capture the packet hosted by RTL_TCP and parse , decode and print the same.
And finally we are able to get some SCM Packet from ERT Gas meter.

{Time:2022-04-18T18:30:55.628 SCM:{ID:57753518 Type:12 Tamper:{Phy:03 Enc:00} Consumption: 389346 CRC:0x6049}}
{Time:2022-04-18T18:31:10.126 SCM:{ID:57753518 Type:12 Tamper:{Phy:03 Enc:00} Consumption: 389346 CRC:0x6049}}
{Time:2022-04-18T18:31:25.125 SCM:{ID:57753518 Type:12 Tamper:{Phy:03 Enc:00} Consumption: 389346 CRC:0x6049}}
{Time:2022-04-18T18:32:09.675 SCM:{ID:57753518 Type:12 Tamper:{Phy:03 Enc:00} Consumption: 389346 CRC:0x6049}}
{Time:2022-04-18T18:32:39.671 SCM:{ID:57753518 Type:12 Tamper:{Phy:03 Enc:00} Consumption: 389346 CRC:0x6049}}
{Time:2022-04-18T18:33:25.667 SCM:{ID:57753518 Type:12 Tamper:{Phy:03 Enc:00} Consumption: 389346 CRC:0x6049}}
{Time:2022-04-18T18:34:39.663 SCM:{ID:57753518 Type:12 Tamper:{Phy:03 Enc:00} Consumption: 389346 CRC:0x6049}}
{Time:2022-04-18T18:35:55.433 SCM:{ID:57753518 Type:12 Tamper:{Phy:03 Enc:00} Consumption: 389346 CRC:0x6049}}
{Time:2022-04-18T18:36:10.156 SCM:{ID:57753518 Type:12 Tamper:{Phy:03 Enc:00} Consumption: 389346 CRC:0x6049}}
{Time:2022-04-18T18:36:40.154 SCM:{ID:57753518 Type:12 Tamper:{Phy:03 Enc:00} Consumption: 389346 CRC:0x6049}}
{Time:2022-04-18T18:37:40.155 SCM:{ID:57753518 Type:12 Tamper:{Phy:03 Enc:00} Consumption: 389346 CRC:0x6049}}

Issues : I have tried to capture what data is actually being captured by RTL_TCP and send to RTLAMR so tried to print bits/bytes/decimal data in differenc ways
{981 111110010101001100000110001100000000010111110100111001000111000100111111101011100100111111110011 [249 83 6 48 5 244 228 113 63 174 79 243]}

we are using RTLAMR as base for our further investigation to capture ERT Gas meter packets. So we want to understand whether the data being captured here is 1) Manchestor encoded data or not?
2) which modulation technique being used here.
3) how we can capture the same data using CC1111 Transciever using custom code. I have tried to capture the data using custom code but that did not work.

Please guide

Also i need to understand few of parameters being used in RTLAMR code:
1 Chiplength
2 Sample rate
3 Date rate units
4 Preamble length
5 packet length

[bemasher]

Most of your questions are answered on this page: https://github.com/bemasher/rtlamr/wiki/Signal-Processing

I will answer all of them here anyway:

• ERT packets are on-off keyed and manchester-coded.
• I've messed with a CC1111 dongle several years ago, but no longer have any of that code.
• Symbols are made up of two chips, high and low, the data is encoded in the transition between them (manchester-coding).
• Sample rate is 32768 Hz, data rate is half that.
• Preamble for each message type is given in https://github.com/bemasher/rtlamr/wiki/Protocol
• Packet length is also given on the protocol page.

[rohitjindal786]

@bemasher need more information related to RTLAMR Code: Signal processing section in wiki page mentions:
"The ERT protocol is an on-off keyed manchester-coded signal transmitted at bit-rate of 32.768kbps. On-off keying is a type of amplitude shift keying. Individual symbols are represented as either a carrier of fixed amplitude or no transmission at all."
but you mentioned above data rate is half of Sample rate.
As per my understanding bit rate or data rate is same . If not pls correct me.

Can you help me with any way that i can ""capture raw data from rtlamr code"" just before any kind of processing. Processing here means verification of Preamble /checksum etc. That would help me alot as i want to understand what Manchestor encoded data is recieved as the raw data . As we are not sure that which encoding is being used its
1G.E.Thomas or
2 IEEE802 Encoding
https://eleif.net/manchester.html , you can refer for both types of menchestor encodings

Please guide.

[rohitjindal786]

@bemasher Thankyou for your prompt reply.
can you comment on my other queries related to Data rate and machestor encoding standard being used out of GE Thomas or IEEE802.

[rohitjindal786]

@bemasher Can you pls help on the above. I tried to capture the raw data as you mentioned using -samplefile but that is not fulfilling my requirement.

[bemasher]

You'll want to use -samplefile which will write samples exactly as they are received from the radio which are uint8 IQ samples.

https://github.com/bemasher/rtlamr/blob/master/flags.go#L35

[rohitjindal786]

@bemasher Thankyou for your prompt reply.
can you comment on my other queries related to Data rate and machestor encoding standard being used out of GE Thomas or IEEE802.