Survey Data File
Survey Single and Survey Sweep modes record the results of each operation to a Survey Data File in the device’s non-volatile memory. The Survey Data File has a simple, human readable format. Each line contains the results of a single survey as a comma separated list. This could be an individual survey or a survey in a sweep. The format of the first item in the list determines if the line contains the results of a single survey or a survey in a sweep.
In order to view the data file, you must first go into Configuration Mode then issue AT+GSDF.
Fields
Each line has the fields listed below:
| ID | Identifies the line as a single survey or part of a sweep and contains the corresponding index |
| Status | Specifies if the survey was a success or failure |
| Lock | GPS lock (# of satellites) |
| Lat | GPS latitude |
| Long | GPS longitude |
| Alt | GPS altitude |
| Time | GPS timestamp (UTC format) |
| Gateways | How many gateways heard the link check request |
| Margin | Signal margin above the demodulation floor (in dBm) |
| RSSIdown | Downlink signal strength (RSSI) |
| SNRdown | Downlink signal-to-noise ratio (SNR) |
| DataRate | TX datarate used |
| Power | TX power used |
Each line in the Survey Data File has fields in the following order. Fields are not labeled to save space.
A field can be empty if its data item is not available or not applicable.
ID, Status, Lock, Lat, Long, Alt, Time, Gateways, Margin, RSSIdown, SNRdown, DataRate, Power
Field Formats
Each field in a line of the Survey Data File is formatted as shown below:
| ID | Lxx for Survey Single and Sxx for Survey Sweep (max 6 characters) |
| Status | S for success, F for failure (1 character) |
| Lock | number of GPS satellites (max 2 characters) |
| Lat | degrees minutes seconds E/W (max 15 characters) |
| Long | degrees minutes seconds N/S (max 15 characters) |
| Alt | altitude (max 6 characters) |
| Time | hours:minutes:seconds month/day/year (19 characters) |
| Gateways | gateways (max 2 characters) |
| Margin | margin (max 2 characters) |
| RSSIdown | rssi (max 3 characters) |
| SNRdown | snr (max 5 characters) |
| DataRate | datarate (2 characters) |
| Power | power (max 2 characters) |
The RSSIdown field does not include the “-” sign in the Survey Data File because its value is always negative.
The maximum size of one line in the Survey Data File is:
| ID | 6 |
| Status | 1 |
| Lock | 2 |
| Lat | 15 |
| Long | 15 |
| Alt | 6 |
| Time | 19 |
| Gateways | 2 |
| Margin | 2 |
| RSSIdown | 3 |
| SNRdown | 4 |
| DataRate | 2 |
| Power | 2 |
| Commas | 12 (12 commas to separate 13 items) |
| + Newline | 1 |
| ———— | ——————————————- |
| Total | 92 bytes |
The device’s non-volatile memory should be capable of storing over 20,000 full lines of survey data before the
memory runs out of space. This result was found using the strategy described below.
Start with 2 MB of space
2 * 1024 * 1024 = 2,097,152 bytes
Subtract 10% for filesystem overhead and LoRa configuration
2,097,152 * 0.9 = 1,887,436.8 bytes
Divide by number of characters per line
1,887,436.8 / 92 = 20,515.6 lines
Examples
The following is an example of a successful Survey Single without GPS lock in the Survey Data File.
L21,S,0,,,,,1,11,82,8.2,9,20
The following is an example of a successful Survey Single with GPS lock in the Survey Data File.
L23,S,10,45 5 58.542 N,93 11 46.980 W,239,21:44:16 12/14/2015,1,12,46,8.5,9,20
The following is an example of a failed Survey Single without GPS lock in the Survey Data File.
L11,F,0,,,,,,,,,7,11
The following is an example of a failed Survey Single with GPS lock in the Survey Data File.
L22,F,10,45 5 58.542 N,93 11 46.980 W,239,21:44:11 12/14/2015,,,,,9,20
The following is an example of a Survey Sweep in the Survey Data File. Note that the 1st, 8th, and 9th lines are
failed surveys which still contain GPS data. The 10th line was a successful survey without a GPS lock.
S1,F,11,45 5 59.994 N,93 11 31.542 W,29,19:47:57 12/11/2015,,,,,7,2
S1,S,11,45 5 59.994 N,93 11 31.542 W,29,19:48:01 12/11/2015,2,8,20,7.2,7,8
S1,S,11,45 5 59.994 N,93 11 31.542 W,29,19:48:05 12/11/2015,1,10,20,7.2,7,14
S1,S,11,45 5 59.994 N,93 11 31.542 W,29,19:48:09 12/11/2015,1,9,22,7.0,7,20
S1,S,11,45 5 59.994 N,93 11 31.542 W,29,19:48:13 12/11/2015,2,11,25,7.2,8,2
S1,S,11,45 5 59.994 N,93 11 31.542 W,29,19:48:17 12/11/2015,2,9,26,7.7,8,8
S1,S,11,45 5 59.994 N,93 11 31.542 W,29,19:48:21 12/11/2015,1,11,24,3.0,8,14
S1,F,11,45 5 59.994 N,93 11 31.542 W,29,19:48:26 12/11/2015,,,,,8,20
S1,F,11,45 5 59.994 N,93 11 31.542 W,29,19:48:39 12/11/2015,,,,,9,2
S1,S,0,,,,,2,11,27,7.7,9,8
S1,S,11,45 5 59.268 N,93 11 37.602 W,29,19:48:47 12/11/2015,2,13,26,7.2,9,14
S1,S,11,45 5 59.178 N,93 11 38.490 W,103,19:48:51 12/11/2015,1,11,28,8.5,9,20
S1,S,11,45 5 59.022 N,93 11 39.930 W,103,19:48:55 12/11/2015,2,9,27,7.0,10,2
S1,S,11,45 5 59.022 N,93 11 40.038 W,139,19:49:00 12/11/2015,2,9,27,7.2,10,8
S1,S,11,45 5 59.022 N,93 11 40.080 W,139,19:49:04 12/11/2015,2,9,27,7.7,10,14
S1,S,11,45 5 59.022 N,93 11 40.116 W,139,19:49:08 12/11/2015,1,8,27,8.2,10,20