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Test Methodologies and developments

Test Methodologies and developments. Matthew Haywood Applications Engineer. Topics Covered. Established approaches to receiver / system testing Conductive vs. Radiated testing Most Evil Waveform Test approaches: next steps. Conductive vs. Radiated Testing.

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Test Methodologies and developments

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  1. Test Methodologies and developments Matthew Haywood Applications Engineer

  2. Topics Covered • Established approaches to receiver / system testing • Conductive vs. Radiated testing • Most Evil Waveform • Test approaches: next steps

  3. Conductive vs. Radiated Testing • Guaranteed replication of signal characteristics achieved by direct RF cable connection between simulator and receiver • Case-by-case considerations for cable, external connection losses aside • Main RF port of simulators designed with conductive testing in mind, i.e. signal levels aligned to nominal received levels at Earth’s surface • Good quality RF cable (1m length) can achieve • Isolation from unwanted interference • Negligible loss of signal level • Signal phase stability for phase-sensitive tests • Fully independent antenna pattern control

  4. Pros and Cons - Radiated • Radiated Testing – Pros • Includes actual antenna - and often LNA - in the test (checks connectivity) • Allows all types of device with an integrated antenna to be tested • Allows testing of product after final assembly, when access to internal RF connections in no longer possible • Radiated Testing – Cons • Does not test antenna performance as RHCP mode of propagation is not established (RX is in the near field) • Can interfere with other users (or be interfered with) if not in a controlled test set-up such as a TEM cell or Anechoic chamber • Exact signal power at antenna is harder to determine (characterisation of test set-up required • Use of MON/CAL port to overcome path loss often results in in-correct CNR at receiver (because it is not correct on the Mon/Cal port) • Multipath can be a problem

  5. Pros and Cons - Conducted • Conducted testing – Pros • Tight control of signal power and inter-system matching • No interference with other users • No multipath due to test set-up • Conducted testing – Cons • Antenna not included in the test • May be difficult to access appropriate point to inject RF • Prevents testing of some products with in-built antennas

  6. Disadvantages of Live-Sky re-radiation • Illegal in many countries • E.G. in the UK, Office of Communications says it breaches the Wireless Telegraphy Act 2006 • Can interfere with other users • As a signal for receiver testing it is not adequate • Not repeatable (constellation, atmospheric delay & signal conditions always changing) • Unknown errors (satellite, control segment, nav data) • Even though the receiver’s antenna may be receiving signals, its performance cannot be tested as the signals are arriving from a point source.

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