© Microhard Systems Inc. Confidential 80
6.0 Register/Command Reference
6.1 AT Commands
Appendix B is a quick reference for the available AT commands; in this sub-section are details regarding
the most commonly used. To invoke an AT command, enter Command Mode, then type AT<command>
[Enter]. Most AT commands have a help string that can be seen by typing AT<command><space>/?
[Enter].
A Answer
Upon completion of tasks being done with the modem in Command Mode, invoking this command will place the
modem back ‘online’ (into Data Mode).
If changes were made to
the modem’s
configuration and it is
intended that those
changes be saved to non-
volatile memory, do so
with the AT command
’&W’ prior to placing the
modem online.
g, G Spectrum Analyzer
This is a very useful feature of the P900. ATg or ATG will provide a display of signal levels received within the
operating environment and frequency range of the modem under test. ATg averages 256 samples, ATG 16,000.
Invoking the ATg command causes the P900 to sweep the operating band and provide a display of both the mean
and peak signal levels, in dBm, found on each channel.
The ‘graphical’ display is limited from –110dBm to –53dBm, and is in 1dB increments. Ignore the leftmost asterisk in
calculations (as below).
How to interpret the display (example):
...
ch 78 -137dBm * No signal was measured on channel 78.
ch 80 -105dBm ******... Mean signal level: -(110-5 (asterisks)) = -105dBm
... Peak signal level: -(110-5 (asterisks) -3 (dots)) = -102dBm
For the P900 Channel 1 is at 902.4MHz (for North America, varies by country & link rate), with subsequent channels
in increments dependent on the link rate. Therefore, to calculate the frequency of channel n: (BW = Channel
Bandwidth in MHz)
Freq channel n = 902.4+ ((n-1) x BW) MHz.
In Identification
The I command returns information about the P900. Use ATI /? for a list of current options.
0 User string. Use ATI0=<string> to save the string.
1 Product Code
2 Firmware CRC check
3 Product Identification (Firmware Version)
4 Firmware Date
5 Firmware Copyright
6 Firmware Time
7 MAC Address
11 Statistics
18 Error log
19, 20 Mesh Timing information.
255 Factory-Configured Options listing
Link Rate
(bps)
Channel
Bandwidth
(kHz)
57600 100
115200 200
172800 250
230400 280
276480 350
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