Philips Semiconductors

PCD3316

CIDCW receiver

Product specification

11 March 1999

23 of 30

9397 750 04824

© Philips Electronics N.V. 1999. All rights reserved.

11. Test information

11.1 Application note on Customer Premises Equipment (CPE) testing

Under certain circumstances, some external CIDCW test equipment may generate

incorrect pulses after the ringing signal becomes inactive. These pulses may cause

the FSK detector of the PCD3316 to respond. Note that this is by no means an

incorrect behaviour of the PCD3316 chip, but a correct detection of incorrect test

stimuli. However, if not known, it may lead to confusing results during testing of the

CPE.

To avoid the issue described above, following work-around can be used:

1. Disable the FSK detection of PCD3316, before and during the ringing signal

detection.

2. Switch on the FSK detection only after a certain period, e.g. 100 ms after the

ringing signal goes inactive.

3. When the first FSK data is detected, e.g ‘55H’ (possible part of channel seizure),

switch off the FSK detection and on again. This will force the FSK detector to

resynchronize and detect the normal FSK data correctly. It may be necessary to

repeat this sequence a number of times to ensure that the data detected really

comes from the channel seizure. Thus, it is recommended to wait for a multiple

number of bytes ‘55H’ to be detected to validate a correct channel seizure.

Attenuation networks to connect the polarity and FSK inputs to

the telephone line.

High-pass filter (cut-off

frequency

≈ 1 kHz) to improve

performance of CAS detection.

a.

Attenuation networks.

b.

High-pass filter.

Fig 16. Application diagrams.

MGK729

820 k

Ω

100 k

Ω

100 k

Ω

820 k

Ω

100 k

Ω

100 k

Ω

POL0

POL1

a/b

b/a

FSKIN

+

FSKIN

−

11

10

14

15

1 nF

1 nF

PCD3316

2.2

µF

(250 V)

2.2

µF

(250 V)

telephone

line

ook, halfpage

MBH996

CASIN

13

120 k

Ω

100 nF

1.8 nF

PCD3316