Protocol analysis
R&S
®
RTP
744User Manual 1337.9952.02 ─ 12
13.15 Custom: Manchester / NRZ (option R&S RTP-K50)M
R&S RTP-K50 is a firmware option that enables the R&S RTP to analyze customizable
serial bus signals encoded by the following coding standards:
●
Manchester
●
Manchester II
●
NRZ Clocked
●
NRZ Unclocked
For analysis, signals encoded in any of these protocols can be triggered and decoded.
Due to the free format description, no search within the decoded events is available.
This chapter describes:
● Custom: Manchester / NRZ protocols...................................................................744
● Custom: Manchester / NRZ configuration.............................................................746
● Custom: Manchester / NRZ trigger....................................................................... 764
● Custom filter..........................................................................................................768
● Custom: Manchester / NRZ decode results.......................................................... 771
● Search on decoded custom Manchester / NRZ data............................................ 772
13.15.1 Custom: Manchester / NRZ protocols
"Manchester" coding is a self-clocked coding scheme also known as phase-shift keying
(or phase encoding, PE). It is used in protocols such as ProfiBus (IEC 61158), DALI
(Digital Addressable Lighting Interface, IEC 60929 and IEC 62386), MVB (Multifunction
Vehicle Bus, part of IEC 61375 for Train Communication Networks, TCN), and Ethernet
10BASE-T (10 Mbit/s, IEEE 802.3i). In terms of a logical Boolean operation, the Man-
chester value of each bit (as per G. E. Thomas) is the exclusive disjunction (XOR) of
the original data value and the clock value. A "0" is expressed by a high-to-low transi-
tion, a "1" by a low-to-high transition. These transitions, which occur at the middle of
each bit period, make the signal self-clocked.
"Manchester II" coding (as per IEEE 802.3) is represented by inverted Manchester val-
ues: a "0" is expressed by a low-to-high transition, a "1" by a high-to-low transition.
NRZ stands for "non-return-to-zero" coding: Typically a "1" is represented by a positive
voltage and a "0" is represented by a negative voltage, with no "zero" voltage state.
NRZ code requires only half the bandwidth of Manchester code, and it can either be
clocked or unclocked. NRZ unclocked signals require a user-defined bit rate and gap
time setting for triggering and decoding.
13.15.1.1 Special features of Manchester coding
In practical protocols, Manchester coding appears in many variations, often employing
deliberate coding violations to encode special waveform features, such as unambigu-
ous synchronization and termination patterns. To adapt to these specific Manchester
implementations and handle ambiguous signals, the option R&S RTP-K50 for Custom
Custom: Manchester / NRZ (option R&S
RTP-K50)M
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