Comparison of Testing Requirements
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Comparison of Type 1 testing requirements from
Telcordia and TIA/EIA
Relevant Standards
There are currently two standards which are used as a guideline to
producing a robust Type 1 Caller ID device. The first standard that
was introduced is from Telcordia, formally called Bellcore. While they
produce a number of standards on the subject of telephony, they
published one document in particular, which is useful as a testing
guideline. This document called SR-3004, "Testing Guidelines for
Analog Type 1, 2, and 3 CPE as Described in SR-INS-002726",
brought together the requirements from a number of other Telcordia
standards to produce a test suite for evaluating a Type 1 Caller ID
device. The version of the standard used in the creation of this
comparison is Issue 2, January 1995. It is expected that Telcordia
will release a revision to this document in the near future and may be
as earlier as the end of 2000. While SR-3004 also addresses the
requirements for a Type 2 and Type 3 CPE, requirements these are
outside the scope of this article.
The other standards body that publishes standards on Caller ID is
TIA/EIA. This group is formed from industry participants who meet on a
regular basis to determine basic requirements for telecommunication
and other electronic equipment. In the case of Caller ID they
currently publish a document called TIA/EIA-716
"Telecommunications Telephone Terminal Equipment – Type 1
Caller Identity Equipment Performance Requirements". The current
issue for this document is November 1998. TIA/EIA-716 is the first in
a series of three documents to be created by TIA and only covers the
requirements for a Type I device. The Type II requirements are in a
separate document called TIA/EIA-777 and TIA will soon publish a third
document, incorporating the requirements for Type 1, 2 and 2.5 in a
single source.
TIA/EIA-716 vs. SR-3004
This article breaks down the Caller ID device requirements into
areas. These being the physical layer and the data layer
The physical layer is defined as the physical properties that
control the transmission of the FSK to the device. These would
include any parameters that can be expressed as a time, a frequency
or an electrical level.
The data layer is defined as the binary data that is sent between
the central office and the receiving device. The data would include
the message type, parameter words, checksum and also the channel
seizure and mark signals preceding the data.
The following tables show the requirements in a point form and
indicate the document section the specification is from.
Physical Layer Requirements
The following table is a quick reference between the physical layer
requirements of TIA/EIA-716 and the requirements of SR-3004.
| |
TIA/EIA-716 |
Telcordia
(Bellcore) SR-3004 |
|
Parameter |
Section |
Requirement |
Section |
Requirement |
|
Mark Frequency |
4.4.1 |
± 1% |
3.1.1
3.1.11
|
± 1%
(± 100 Hz) 3
|
|
Space Frequency |
4.4.1 |
± 1% |
3.1.1
3.1.11
|
± 1%
(± 100Hz) 3
|
|
Baud Rate |
4.4.4 |
± 1% |
3.1.1
3.1.11
|
± 1%
(1150 to 1250) 3
|
|
Mark Level |
4.4.2 |
19 mV to 476mV1 |
3.1.2
3.1.11
|
-12 to -32 dBm2
(-12 to > – 40 dBm) 3
|
|
Space Level |
4.4.2 |
12 mV to 476mV1 |
3.1.2
3.1.11
|
-12 to -36 dBm2
(-12 to > – 40 dBm) 3
|
|
Reject Level |
4.4.2 |
3 mV1 |
3.1.11 |
(-50 dBm)3 |
|
Twist |
4.4.3 |
+10 dB / -6 dB |
3.1.3 |
± 10 dB |
|
Ringing On time |
4.3.1 |
Meets T1.401 |
3.1.4 |
Duration ³ 200mS |
|
Ringing Off time |
4.3.1 |
Meets T1.401 |
3.1.4 |
2.0 to 6.0 Seconds |
|
Interfering Noise |
4.4.5 |
-18 dB 60 £ f
-12 dB 60 £ f £
120 Hz
-6 dB 120 £ f £
200 Hz
+25 dB 200 £ f £
3200 Hz
+6 dB f ³ 3200 Hz
|
3.1.5 |
-20 dB 200 £ f
+25 dB 200 £ f £
3200 Hz
-20 dB f ³ 3200 Hz
|
|
Echo Noise |
4.4.6 |
Delay 1 to 3 ms
Atten. 13 dB and 26 dB
|
n/a |
Not Specified |
|
Channel Seizure Dropout |
4.5.3 |
£ 10 ms |
3.1.10 |
£ 10 ms |
|
Mark Signal Dropout |
4.5.3 |
Not Specified |
3.1.10 |
£ 10 ms |
|
Markout |
4.6.8 |
0 to 4400 ms |
n/a |
Not Specified |
|
Channel Seizure delay |
4.3.1 |
250 ms to 3600 ms |
3.1.8
3.1.11
|
250 ms to 3600 ms
(100 ms to 3600 ms) 3
|
|
Delay to Ringing after Data |
4.3.1 |
³ 200 ms |
n/a |
Not Specified |
|
Immunity to False Ringing |
4.3.1 |
Display should not change |
3.1.6 |
Display should not change |
|
Reception after power ringing |
n/a |
Not Specified |
3.1.7 |
After 2 to 20 Rings |
1 Specified from a 900 ohm source, and measured in an open
circuit termination
2 Specified from a 900 ohm source, and measured in a 600
ohm termination
3 Indicates an extended operating condition. The extended
operating conditions cover a wider set of requirements not all of
which are not shown in the table above.
Data Layer Requirements
The following table is a quick reference between the data layer
requirements of TIA/EIA-716 and the requirements of SR-3004.
| |
TIA/EIA-716 |
Telcordia
(Bellcore) SR-3004 |
| |
Section |
Requirement |
Section |
Requirement |
|
Channel Seizure |
4.5.1 |
70 to 320 Bits |
3.2.1 |
280 to 320 Bits
(200 to 350 Bits)3
|
|
Mark Signal |
4.5.2 |
40 to 525 Bits |
3.2.1 |
160 to 200 Bits
(70 to 210 Bits)3
|
|
Stuffed Mark Bits |
4.6.6 |
0 - 100 bits / packet
500 bits / message max
|
3.2.5 |
0 to 25 Bits between message words |
|
Message Type Verification |
4.6.2 |
Ignore when invalid |
3.2.2 |
Ignore or display error when invalid |
|
Message Length errors |
n/a |
Not Specified |
3.2.3 |
Ignore or display error when invalid |
|
Checksum Error |
4.8.1 |
Ignore or display error |
3.2.4 |
Ignore or display error when invalid |
|
Parameter Type Verification |
4.6.4 |
Ignore when invalid |
n/a |
Not Specified |
|
Parameter Length errors |
n/a |
Not Specified |
3.2.6 |
Ignore or display error when invalid |
|
Space Bits after Checksum |
4.6.8 |
Ignore |
n/a |
Not Specified |
|
SDMF VMWI |
4.7.5.1 |
Valid data should correctly set the indicator |
3.2.6 |
Valid data should correctly set the indicator |
|
MDMF VMWI |
4.7.5.2 |
Valid data should correctly set the indicator |
3.2.6 |
Valid data should correctly set the indicator |
|
Out of Range data |
4.8.3 |
Display, ignore or correct |
n/a |
Not Specified |
3 Indicates an extended operating condition. The extended
operating conditions cover a wider set of requirements not all of
which are not shown in the table above.
Summary
The two tables above show that, in some cases, it is the TIA
standard that has the more stringent requirement and in other cases it
is the older SR-3004. In a robust design it may be possible to meet
the requirements of both standards in a single implementation. This
provides the best performance in the field since many of the
requirements have come directly from field experience within North
America.
The next article in the series will compare the requirements for a
Type 2 Caller ID device.
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