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ETALDOC 364/4

Page 1 of 3

January 2001

PRODUCT DATA SHEET

UNIVERSAL 16kHz METERING

P2692

SIGNAL FILTER

Features

∗

Miniature construction

∗

>40dB attenuation at 16kHz

∗

Matches 600

Ω

and complex impedances

∗

Minimal in-band attenuation

DESCRIPTION

Many telephone networks bear 16kHz metering
signals at amplitudes sufficient to operate simple
relay-type apparatus without amplification on
customers' premises. Modems containing
semiconductor line-hold circuits are easily upset by
these large signals because the voltage swing may
exceed the standing DC level. The P2692 filter

deals effectively with this by problem suppressing
the metering signals, its attenuation ensuring that,
in the worst case, their level is reduced to less
than 0.2Vrms across the line-hold. The claimed
performance is maintained even when the drive is
the greatest of which the network is capable and
with simultaneous maximum DC superimposed.

CONSTRUCTION

to Electronic Techniques

(Anglia) Limited

P2692

ETALDOC 364/4

Page 2 of 3

January 2001

Safety

Worst-Case Drive

A non-safety-critical component.

Line to Line

Maximum:
Supports:

200V DC.
75V DC plus maximum ringing
voltage.

This is determined by the German test conditions
which are the most stringent. The feeder bridge
represents a source resistance of 200

Ω

at the

simulated line terminals. This ‘line’ is loaded with a
resistance of 200

Ω

and the 16kHz level adjusted

to +22dBm/600. The source voltage is then
+28dBm/600 or 19.50Vrms.

TEST CONDITIONS

Attenuation Test*

See circuit Fig. 1 Note that C1 etc. need not be
present.

Frequency

16kHz ±160Hz

Source voltage

up to 20Vrms

up to 70mA

Temperature

-10ºC to +70ºC

*IN and OUT terminals MUST be respected but the
filter may be inverted because the transformer
interwinding impedances are very high, so avoiding
imbalance effects.

PERFORMANCE CLAIMS

Attenuation

Exceeds 40dB.

NOTE: Further attenuation at the load may be
provided by roll-off in the transformer.

P1200 and P2001

approx 11.0dB

P1165

approx 0.5dB

P2781

negligible

Input Impedance

With 15.92 – 16.08 at AB.
With 22nF input capacitor C3, >400

Ω

(almost pure

capacitance)
Without 22nF input capacitor, >1k

Ω

DC Resistance

Pins 1-2: 12.5-14.5

Ω

The Attenuation is defined as A =20 log dB

430

Ω

DUMMY
FEEDER
BRIDGE

CURRENT

SINK

P2781

200

Ω

P2692

ETALDOC 364/4

Page 3 of 3

January 2001

For matching to transformers and reference
impedances not specified below, please contact
Profec Technologies.

Z ref

Transformer

Return Loss, dB

ohms

300Hz

500Hz

2500Hz

3400Hz

Germany

P1200

2.2

22 ± 5%

910 2%

220

Ω

P2001

2.2

22 ± 5%

910 2%

(820

Ω

//115nF)

P1165

2.2

6.8 ± 5%

22 ± 5%

910 2%

P2781

2.2

33 ± 5%

Not fitted 910 2%

600

Ω

P1200

4.7

22 ± 5%

Not fitted 560 2%

P2001

4.7

22 ± 5%

Not fitted 560 2%

P1165

4.7

Not fitted

Not fitted 560 2%

P2781

4.7

Not fitted

Not fitted 430 2%

COPYRIGHT

CAUTION

This signal filter has been designed and
characterized for use with ETAL line isolating
transformers only. Satisfactory performance
cannot be guaranteed with other components.

ETAL and P2692 are Trade Marks of Profec
Technologies Ltd.
The Trade Mark ETAL is registered at the UK
Trade Marks Registry.

Profec Technologies Ltd. is the owner of the design
right under the Copyright Designs and Patents Act
1988 and no rights or licences are hereby granted
or implied to any third party.

T R A N S F O R M I N G T H E F U T U R E

Profec Technologies Ltd., 10 Betts Avenue, Martlesham Heath, Ipswich, IP5 3RH, England

Telephone: +44 (0) 1473 611422

Fax: +44 (0) 1473 611919

Websites: www.etal.ltd.uk

www.profec.com

Email:

info@etal.ltd.uk

sales@profec.com

ISO 9001

FM 25326

TRANSFORMER

C 2

C 1

C 3

CURRENT

SINK

–

Z ref