Trango Broadband M900S AP Search, Rssi Command for Antenna Alignment, SU Alignment Using LEDs

Deployment

In conjunction with the RSSI command, it is also useful to perform the apsearch command that will tell you which AP is providing an adequate signal at the location of the SU.

AP Search

1.Ensure AP is in Opmode “On.”

2.Run the apsearch command to verify which AP is providing the strongest signal strength.

#> apsearch

Press [space] then [enter] to stop

In this example, an AP is detected on channel 1, polarization horizontal. Further, the Base ID is 1234, and the MAC address is 00 01 DE 15 5C D0.

1	906	Hz	1234	DE 15	5C	D0	[H:	-32	dBm] [V:	-50	dBm] [E:	-78	dBm]
2	912	Hz	----	FF FF FF		FF [H:		-80	dBm] [V:	-86	dBm] [E:	-99	dBm]
3	918	Hz	----	FF FF FF		FF [H:		-85	dBm] [V:	-86	dBm] [E:	-99	dBm]
4	924	Hz	----	FF FF FF		FF [H:		-82	dBm] [V:	-81	dBm] [E:	-99	dBm]

RSSI Command for Antenna Alignment

Step 1 Telnet into the SU (while in Opmode “OFF”). Use the freq and antenna command to note the radios current settings.

Step 2 Run the rssi command. The telnet session screen will begin a continuous readout of the received signal strength. As you read the RSSI reading, move the antenna in the horizontal and vertical planes until the maximum RSSI reading is achieved. To allow for plenty of fade margin, we recommend a continuous RSSI reading of -78 dBm or better. An RSSI of –88 dBm will allow you to establish a wireless link, but there may not be sufficient fade margin for reliable and continuous operation.

Example 1 has the wrong freq and antenna settings: #> rssi

[	1]	peak -80 dBm		avg -93 dBm
[	2]	peak -80 dBm		avg -97 dBm
[	3]	peak -99	dBm	avg -99	dBm
Example 2 has the correct freq and antenna settings:
#> rssi		peak -33	dBm	avg -74	dBm **
[	1]
[	2]	peak -33	dBm	avg -68	dBm ***
[	3]	peak -33	dBm	avg -64	dBm ****

Step 3 If it is not possible to receive an adequate RSSI reading, it may be necessary to reorient the AP (up/down, left/right), to increase the output power of the AP, or to move the SU to a location with better line-of-sight conditions to the AP. Alternatively consider using external antennas on either the AP or SU or both.

Once you are satisfied with the RSSI reading, tighten down the SU in the optimum position. To stop the RSSI continuous readout, hit SPACE ENTER.

SU Alignment Using LEDs

The LED RSSI indicators on the bottom of the radio provide a handy alignment tool. If all four LEDs are lit, the unit is receiving –60 dBm or stronger. If no LEDs are lit, there is not sufficient signal strength to establish a wireless link.

Lit LEDs	Signal Strength
0 LED	-80 dBm
1 LED	-75 dBm
2 LED	-70 dBm
Trango Broadband Wireless — User Manual M900S Rev C		Page 34