Cable Integrity and Cable Loss Test in GSM

Cable Integrity and Cable Loss Test in GSM, the transmit antenna, to the wattmeter, cable integrity test, record reading, test transmitter, cable loss.

Cable test is first understanding for any RF Engineer here i write how to test cable integrity and Cable loss and testing of Transmitter in gsm.

Cable Integrity Test

Cable Integrity Test

  • Cable integrity is checked by measuring VSWR.
  • A good known cable is connected from the test transmitter to the wattmeter.
  • The cable under test is placed between the wattmeter & 50 Ohms load.
  • Forward and reverse power levels are measured and VSWR can be calculated as ,

  • Each cable should be checked and any that exhibit greater than 1.2 : 1 VSWR must be replaced.
  • Cable integrity check must be performed on all jumpers and antenna feedlines.

Cable Loss

Cable Loss

  • All cables used for testing must be measured and clearly labelled with insertion loss before they are used.
  • These are normal wear items and so it is important to replace any cables that become kinked or frayed or that are worn or damaged connectors.

Step 1 Test

  • Connected a cable ‘A’ directly to the wattmeter.
  • Terminate the other end of the wattmeter with a 50 ohms resistance.
  • Insert 1 Watt element in forward position.
  • Adjust to full deflection .
  • Record reading ‘A’

Step 2 Test

Cable loss test

  • Connect cable ‘B’ as shown.
  • Turn transmitter on.
  • Record reading ‘B’.
  • Cable Loss for cable B in dB = 10 log10(B/A)

Transmitter Setup

  • If the propagation test is being done for model tuning to produce a generic model for macro cells, then a high point in the particular area has to be selected.
  • The transmitter and the transmit antenna will be placed at this point (say the roof of the building ).
  • The transmit antenna is connected to the transmitter via a RF cable.
  • Check to see that the cable is connected properly and tight.
  • Loosely connected or faulty cable can increase the VSWR.
  • A test frequency has to selected from the frequency band allocated to the operator. Set the transmitter to this test frequency.

test transmitter

Article Topics :

cable loss, cable integrity, transmitter, integrity, wattmeter, vswr gsm, vswr