BCD436HP/536HP GPS & P25 Adjustment Mode

Summary: Using a GPS receiver for location-based scanning and the P25 Adjustment mode for tuning digital decode thresholds.

Location-Based Scanning With a GPS

A compatible NMEA GPS lets the scanner automatically avoid and unavoid departments and sites as you move.

• BCD436HP: connect using the 4-pin mini plug.
• BCD536HP: it has a 9-pin RS-232 male serial connector; set the serial port to 4800 bps.

A good use: set the location of each transmitter of a multi-site system and a range of about 30 miles, so the scanner avoids and unavoids sites as you move. You can also give departments in a site their own locations and ranges. Antenna positions are listed on RadioReference and in the FCC’s Antenna Structure Registration.

• After the initial GPS review the scanner avoids and unavoids sites and departments according to the scanner range and each item’s range.
• After a power cycle, everything is unavoided until the GPS is reacquired and the review completes.
• If the GPS is unplugged or loses satellites, the last known location is used.
• Sites and departments with locations set that are out of range are temporarily avoided.

Set your GPS format and baud rate under Set Your Location and Range, Set Up GPS. See BCD436HP/536HP Setting Your Location, Range & Service Types and BCD436HP/536HP Managing Favorites Lists, Location Control & Scan Selection.

P25 Adjustment Mode

Lets you see how the digital decode threshold is behaving and set a starting point for a site or conventional channel.

1. Enter the mode: BCD536HP – Func then Vol (repeat to exit). BCD436HP – press Vol, then Func, then Vol (press Vol to exit).
2. Set P25 Threshold Mode to Manual in the Site Options (or the System Options for a conventional channel).
3. Press Func + Dept to hold on a site, or hold on a digital channel.
4. The first line shows the digital error rate and decode threshold (0-20); the second shows the threshold levels for the site.
5. Let it monitor for several minutes. The error rate should fall and the thresholds settle. Note the stable value – the optimum decode threshold.
6. BCD536HP: turn the scroll control (BCD436HP: press Func and turn) to set the manual start level nearest the optimum. It’s remembered for that site as the starting point for auto-tuning.