Digital Radiocommunication Tester R&S CMD80

Measurement technology

Measurements are based on ultramodern digital signal processing. The results are thus available within the shortest possible time, which means an enormous benefit in speed-dictated mass production. DSP technology has two important benefits: measurement functions can be enhanced by software upgrades and new measurement techniques can be added solely by software modifications. The individual measurements for the various standards are derived directly from the relevant specifications and are preconfigured. Measurements can thus be performed without in-depth knowledge of the relevant network.

Basically, CMD80 provides two different measurement modes for each network. Measurements can be performed either as a module test (ie without call setup to the DUT) or as a manual test with full signaling. In the latter case a call setup for performing the measurement can be made both from the base station (which is simulated by the CMD80) and from the mobile. In this mode it is also possible to set up a call with voice loopback. The audio data picked up by the microphone of the mobile phone are buffered in the CMD80 and reflected to the mobile under test after a delay of about two seconds. In this way speech quality of the DUT can be verified.

In the signaling mode, implicit hand-offs can be made within the same standard (ie a D-AMPS handoff to another digital traffic channel – a new channel number – or changeover to another timeslot at the same TDMA frequency) as well as handoffs to other standards, if defined. This is an important criterion for testing multimode/ multiband mobile phones. The measurements themselves are adapted to the relevant transmission standard.

(1) The HOME menu allows simple selection of mobile radio standard (CDMA, TDMA, analog) and frequency band (Cellular, PCS)

(2) The test menus are divided into two sections; mobile-specific measurement results are displayed on the left, the main settings of the BS signal on the right.

(3) In the IS-136 mode the CMD can send a user-defined short message (SMS) to the mobile.

CDMA
Code Division Multiple Access (CDMA) is a new concept in wireless communications. It has gained widespread international acceptance by cellular radio system operators as a method that will increase both their system capacity and their service quality.
In addition to transmitter and receiver tests, power control tests play an important role for CDMA. This is more true since power control mechanisms have a decisive influence on the network capacity.
The main CDMA tests include:
Power control measurements

Open-loop time response
Gated output power
Minimum output
Maximum output

Receiver quality measurements

Frame error rate (FER) measurements
Additionally with AWGN generator (option B81) to simulate noise that is caused by other CDMA calls at the same frequency

Transmitter quality measurement

Carrier feedthrough and I/Q imbalance
Carrier frequency error and transmit time error
Waveform quality (r factor)
Phase error
Magnitude error
Error vector magnitude

4) After registration of the mobile station in the MANUAL TEST mode, the quality of the mobile under test can immediately be examined. In-depth measurements are available in submenus at the push of a button.

(5) The open-loop time response test provides a graph of the mobile station output power as a function of time when the mobile station is commanded via open-loop power control to change its output power.

(6) The gated output of the RF carrier can be displayed in several formats, ie FULL DISPLAY, RISING EDGE or FALLING EDGE.

) In the RECEIVER QUALITY menu the tester performs the receiver quality test and displays the frame error rate over the interval of the most recent number of frames.

TDMA

D-AMPS (Digital Advanced Mobile Phone Service)

is a digital version of AMPS, the original analog standard for cellular phone service in the United States. Both D-AMPS and AMPS are now used in many countries. D-AMPS adds Time Division Multiple Access (TDMA) to AMPS to get three users for each AMPS channel, tripling the number of calls that can be handled on a channel. D-AMPS is known as IS-136 from the Electronics Industries Assocation/Telecommunication Industries Assocation (EIA/TIA).

As with CDMA, the various measurements for IS-136 are subdivided into groups. The main IS-136 tests include:

Transmitter measurements

Adjacent channel power (due to modulation/due to switching), six adjacent/alternate channels
Power versus time measurement
Origin offset (carrier crosstalk)
I/Q imbalance (measure of uneven gain in the I/Q path of the transmitter modulator)
Frequency error
Amplitude droop (level difference between the start and end of a TDMA burst)
Phase error
Magnitude error (amplitude error)
Error vector magnitude (magnitude of the vectorial error function versus time)

Receiver measurements

Bit error rate measurement
Time alignment (in manual test only)
SMS transfer from base to mobile station (in manual test only)
Simulation of mobile assisted handoff (MAHO) – in manual test only

) The adjacent channel power measurement allows the user to measure the adjacent, first, and second alternate channel power and display the results in a frequency domain view.

) The phase error measurement allows the user to measure the difference in phase between the measured signal from the mobile station transmitter and an ideal signal waveform.

(10) The mobile assisted handoff (MAHO) report displays the results of the mobile station measurement report, showing the current base station channel in use, its RSSI (received signal strength indication), and the BER range (bit error information estimated by the mobile station).

Analog

AMPS (Advanced Mobile Phone Service), N-AMPS

is a standard system for analog signal cellular telephone service in the United States and is also used in other countries. It is based on the initial frequency spectrum allocation for cellular service by the Federal Communications Commission (FCC) in 1970. Introduced by AT&T in 1983, AMPS became the most widely deployed cellular system in the United States.

TACS (Total Access Communications System), J/N/E-TACS

Signaling and measurements for the TACS implementations are very similar to those for the AMPS standard, with only a few minor changes. The channel ranges and their associated frequency assignments are different from the AMPS standard, and the default values for many parameters are adjusted to appropriate values for the TACS standards.

Within the various AMPS/TACS measurements both the RF parameters and the audio signal of the mobile phone are investigated.

The main AMPS/TACS tests include:
Carrier power
Carrier frequency error
SAT frequency error/peak
deviation
ST frequency error/peak deviation
Carrier power measurement
Receiver measurements

Sensitivity
Hum/noise
Harmonic distortion
Audio frequency response

Transmitter measurements

Hum/noise
Modulation noise/distortion
Audio frequency response
Modulation limiting

(11) Within the MODULATION LIMITING menu CMD80 measures the maximum frequency deviation which the mobile transmitter allows.

(12) When the tester measures the audio frequency response in normal mode, a de-emphasis filter is active and the configuration menu can be used to set limit lines for the measurement.

(13) The modulation noise and distortion result is highlighted if the percentage of modulation noise and distortion exceeds the limit specified in the configuration menu.


		Miscellaneous Measurement technology Measurements are based on ultramodern digital signal processing. The results are thus available within the shortest possible time, which means an enormous benefit in speed-dictated mass production. DSP technology has two important benefits: measurement functions can be enhanced by software upgrades and new measurement techniques can be added solely by software modifications. The individual measurements for the various standards are derived directly from the relevant specifications and are preconfigured. Measurements can thus be performed without in-depth knowledge of the relevant network. Basically, CMD80 provides two different measurement modes for each network. Measurements can be performed either as a module test (ie without call setup to the DUT) or as a manual test with full signaling. In the latter case a call setup for performing the measurement can be made both from the base station (which is simulated by the CMD80) and from the mobile. In this mode it is also possible to set up a call with voice loopback. The audio data picked up by the microphone of the mobile phone are buffered in the CMD80 and reflected to the mobile under test after a delay of about two seconds. In this way speech quality of the DUT can be verified. In the signaling mode, implicit hand-offs can be made within the same standard (ie a D-AMPS handoff to another digital traffic channel – a new channel number – or changeover to another timeslot at the same TDMA frequency) as well as handoffs to other standards, if defined. This is an important criterion for testing multimode/ multiband mobile phones. The measurements themselves are adapted to the relevant transmission standard. (1) The HOME menu allows simple selection of mobile radio standard (CDMA, TDMA, analog) and frequency band (Cellular, PCS) (2) The test menus are divided into two sections; mobile-specific measurement results are displayed on the left, the main settings of the BS signal on the right. (3) In the IS-136 mode the CMD can send a user-defined short message (SMS) to the mobile. CDMA Code Division Multiple Access (CDMA) is a new concept in wireless communications. It has gained widespread international acceptance by cellular radio system operators as a method that will increase both their system capacity and their service quality. In addition to transmitter and receiver tests, power control tests play an important role for CDMA. This is more true since power control mechanisms have a decisive influence on the network capacity. The main CDMA tests include: Power control measurements Open-loop time response Gated output power Minimum output Maximum output Receiver quality measurements Frame error rate (FER) measurements Additionally with AWGN generator (option B81) to simulate noise that is caused by other CDMA calls at the same frequency Transmitter quality measurement Carrier feedthrough and I/Q imbalance Carrier frequency error and transmit time error Waveform quality (r factor) Phase error Magnitude error Error vector magnitude (4) After registration of the mobile station in the MANUAL TEST mode, the quality of the mobile under test can immediately be examined. In-depth measurements are available in submenus at the push of a button. (5) The open-loop time response test provides a graph of the mobile station output power as a function of time when the mobile station is commanded via open-loop power control to change its output power. (6) The gated output of the RF carrier can be displayed in several formats, ie FULL DISPLAY, RISING EDGE or FALLING EDGE. (7) In the RECEIVER QUALITY menu the tester performs the receiver quality test and displays the frame error rate over the interval of the most recent number of frames. TDMA D-AMPS (Digital Advanced Mobile Phone Service) is a digital version of AMPS, the original analog standard for cellular phone service in the United States. Both D-AMPS and AMPS are now used in many countries. D-AMPS adds Time Division Multiple Access (TDMA) to AMPS to get three users for each AMPS channel, tripling the number of calls that can be handled on a channel. D-AMPS is known as IS-136 from the Electronics Industries Assocation/Telecommunication Industries Assocation (EIA/TIA). As with CDMA, the various measurements for IS-136 are subdivided into groups. The main IS-136 tests include: Transmitter measurements Adjacent channel power (due to modulation/due to switching), six adjacent/alternate channels Power versus time measurement Origin offset (carrier crosstalk) I/Q imbalance (measure of uneven gain in the I/Q path of the transmitter modulator) Frequency error Amplitude droop (level difference between the start and end of a TDMA burst) Phase error Magnitude error (amplitude error) Error vector magnitude (magnitude of the vectorial error function versus time) Receiver measurements Bit error rate measurement Time alignment (in manual test only) SMS transfer from base to mobile station (in manual test only) Simulation of mobile assisted handoff (MAHO) – in manual test only (8) The adjacent channel power measurement allows the user to measure the adjacent, first, and second alternate channel power and display the results in a frequency domain view. (9) The phase error measurement allows the user to measure the difference in phase between the measured signal from the mobile station transmitter and an ideal signal waveform. (10) The mobile assisted handoff (MAHO) report displays the results of the mobile station measurement report, showing the current base station channel in use, its RSSI (received signal strength indication), and the BER range (bit error information estimated by the mobile station). Analog AMPS (Advanced Mobile Phone Service), N-AMPS is a standard system for analog signal cellular telephone service in the United States and is also used in other countries. It is based on the initial frequency spectrum allocation for cellular service by the Federal Communications Commission (FCC) in 1970. Introduced by AT&T in 1983, AMPS became the most widely deployed cellular system in the United States. TACS (Total Access Communications System), J/N/E-TACS Signaling and measurements for the TACS implementations are very similar to those for the AMPS standard, with only a few minor changes. The channel ranges and their associated frequency assignments are different from the AMPS standard, and the default values for many parameters are adjusted to appropriate values for the TACS standards. Within the various AMPS/TACS measurements both the RF parameters and the audio signal of the mobile phone are investigated. The main AMPS/TACS tests include: Carrier power Carrier frequency error SAT frequency error/peak deviation ST frequency error/peak deviation Carrier power measurement Receiver measurements Sensitivity Hum/noise Harmonic distortion Audio frequency response Transmitter measurements Hum/noise Modulation noise/distortion Audio frequency response Modulation limiting (11) Within the MODULATION LIMITING menu CMD80 measures the maximum frequency deviation which the mobile transmitter allows. (12) When the tester measures the audio frequency response in normal mode, a de-emphasis filter is active and the configuration menu can be used to set limit lines for the measurement. (13) The modulation noise and distortion result is highlighted if the percentage of modulation noise and distortion exceeds the limit specified in the configuration menu.


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