Tac/Com Control Head Manual

SM06 Rev. 4.10

3.9.1.3LIST+PRIORITY Scanning

In this mode, both LIST & PRIORITY features are combined, so that a list can be checked while still periodically testing for activity on two priority channels. This is a new feature and only exists on software revisions 2.13 and later for Tac/Com II, and 1.45 and later for Tac/Com I controls. In this case, priority allocations remain per the normal priority mode, but list channels have a lower priority than the 'home' channel, and are scanned only when there is not any activity on the other three.

Note for NTX Transceivers:

When CTCSS tones are enabled, the access time for the decoder is added to the LIST

+PRIORITY scanning time, dramatically reducing receive audio intelligibility. NAT therefore recommends that the combination of CTCSS tones and LIST + PRIORITY scan should be avoided for these units.

3.9.1.4AM Scanning

While this was not an original feature of Tac/Com and the NT136-PAS multi-mode transceiver, it is now fully implemented. Some hardware updates are required to the transceiver (below s/n 1018) to achieve the required sensitivity for fast-lock AM reception, but coupled with current software, it can provide scanning with AM levels down to 2.0 uV. Because of the electrically noisy environment aircraft present, squelch thresholds must be much higher for AM receivers than for FM (2-3.0 uV versus 0.5 uV). When scanning, the effective range of coverage will be smaller for AM than for FM signals of the same strength.

3.9.1.5Scanning on other systems

On Midland Syn-Tech I radios, channels added to the scan list will have the letters 'a' or 'b' added to the end of the ID label display. The status line is used to select whether list 'b' or both list 'a' and 'b' are used in the SCAN mode. Only list 'a' channels are used in the priority mode. Scanning is not provided for Wulfsberg radios due to their very long synthesizer lock up times, which preclude scanning.

3.10NAT NTX138 Wide-band/Narrow-band Operation

The NAT NTX138 radios are capable of operating in either a wideband mode (5.0 kHz modulation) or narrowband (2.5 kHz modulation) mode. These modes are largely determined by the operating system used by the radio, and the associated channel spacing.

See section 3.7.1 for wide/narrow band display indication.

Page 3-28

Jan 4, 2006

ENG-FORM: 806-0106.DOT

 

CONFIDENTIAL AND PROPRIETARY TO NORTHERN AIRBORNE TECHNOLOGY LTD.