Instruction manual

Optional Equipment Installation

110 025-9416

6. If an extender card was used, remove it and reinstall the trunk card.

If a second trunk card was removed for the adjustment procedure, reinstall it.

7. Replace the top cover of the paging terminal and secure it with screws.

DUAL MULTI-FREQUENCY (MF) DECODER

The multi frequency decoder option (Part No. 702-9197) allows the terminal to accept MF digit

feed from direct inward dial (DID) trunks or E&M 2- or 4-wire trunks emulating DID.

Note: MF is not the same as DTMF (touch-tone) signaling. The multifrequency option will

not decode DTMF feed digits.

MF is a dual-tone signaling method similar to the common touch-tone DTMF (dual tone multi

frequency) protocol. Both formats use two combined tones. MF tones, however, are different

frequencies from DTMF tones. Also, the MF protocol involves rigid timing constraints and

framing characters, so that a DID line with four feed digits actually sends six characters which

can NOT decode properly as DTMF.

MF service can be indirectly tested with most RF service monitors, using their DTMF decoders

AC coupled to the telco pair. If MF feed digit service decodes properly as DTMF characters with

no framing digits, then contact the telco service provider to correct the situation. If feed digits

plus two extra characters are observed and do not properly decode as DTMF and if the tone

bursts are not clipped, the MF digits are probably acceptable. The telco technician should have

an MF decoder to verify feed digits if necessary.

The MF option board (Part No. 702-9297) installs onto the dual trunk board to decode these

tones. Essentially, it provides a specialized tone decoder chip for each half of the dual trunk.

JP1 is used only for production testing of MF tone generation. Table 13 shows tone pairs for MF

and DTMF protocols to illustrate the differences.

Table 13. MF and DTMF Tone Pair Comparison

MF Format Tone Pair Frequencies

Coded Digit Name MF Format Tones DTMF Format Tones

1 1 700, 900 697, 1209

2 2 700, 1100 697, 1336

3 3 900, 1100 697, 1477

4 4 700, 1300 770, 1209

5 5 900, 1300 770, 1336

6 6 1100, 1300 770, 1477

7 7 700, 1500 852, 1209

8 8 900, 1500 852, 1336

9 9 1100, 1500 852, 1477