Summitmas I Bld., 4th Floor Jl. Jend. Sudirman Kav. 61~62 Jakarta Phone : 62-21-5201215 Fax : 62-21-5213482

Dear Sirs,

This is to report you trouble shooting activity at Jorong and Asam-asam

A. General Information

Site Name : Jorong and Asam-asamService Area : Banjarmasin (South Kalimantan)Problem Description : Suspect Interferences on this hopDetail of Equipment : DMR 5000s from Indosat Project 108 HopsWorking Frequency : 5GHzCapacity : 3 x STM-1Customer : IndosatAction Date : - August 28, 2013 Jorong

- August 29, 2013 Asam-asam

B. Problem Bad Performance on this hop due to fading and Interferencess

suspected

C. Investigation1. Interferences check via PNMT at Jorong Side

Internal InterferencesThis test are mentioned to figure the Internal interferences level on each system by observe the receive level at jorong side when the TX on correlated system at Asam-asam is muted.

Sys#1 Sys#2

Sys#3 Sys#4Pic 1 Internal interferences test at Jorong via PNMT

External Interferences

This test are mentioned to figure the External interferences level on each system by observe the receive level at jorong side when the TX on all system at Asam-asam are muted.

Pic 2 External interferences test at Jorong via PNMTBoth interferences tests above shown there was no interferences signal captured by PNMT at Jorong

2. Interferences check via Spectrum Analyzer at Jorong Side Internal Interferences

On this test, we observe the response of spectrum analyzer for each frequency channel band width when the TX on correlated system at Asam-asam is muted.

Sys#1 Sys#2

Sys#3 Sys#4Pic 3 Internal interferences test at Jorong via Spectrum Analyzer

External InterferencesOn this test, we observe the response of spectrum analyzer for each frequency channel band width when the TX on all system at Asam-asam are muted.

Interferences

Sys#1 Sys#2

Sys#3 Sys#4Pic 4 External interferences test at Jorong via Spectrum Analyzer

From both interferences tests procedure by using Spectrum Analyzer, there was found External Interferences on lower space band width area of RX channel Sys#1 at Jorong. The ideal bandwidth which is free form interferencess are 80MHz for each system which is 40MHz to the lower space and 40 MHz to the upper space form its center/ working frequency.As we know the working channel frequency of RX Sys#1 is 4730MHz, so the free space/ band width which is should free from interferencess signal is from 4690 MHz to 4770MHz, for more detail please refer to picture below

Pic 5 Spectrum Analyzer responses of RX sys#1 at JorongThe picture above shown there is some noise on lower space bandwidth which is indicated interferencess

Interferences

Working Bandwidth

Lower Space Bandwidth

Upper Space Bandwidth

Center frequency 4730MHz

Interferences

3. Interferences check via PNMT at Asam-asam Side Internal Interferences

This test are mentioned to figure the Internal interferences level on each system by observe the receive level at Asam-asam side when the TX on correlated system at Jorong is muted.

Sys#6 Sys#7

Sys#8 Sys#9Pic 5 Internal interferences test at Asam-asam via PNMT

External InterferencesThis test are mentioned to figure the External interferencess level on each system by observe the receive level at Asam-asam side when the TX on all system at Jorong are muted.

Pic 6 External interferences test at Asam-asam via PNMT

The result of both test above, shown there was no interferences captured by PNMT form either Internal or external sources.

4. Interferences check via Spectrum Analyzer at Asam-asam Side Internal Interferences

On this test, we observe the response of spectrum analyzer for each frequency channel band width when the TX on correlated system at Asam-asam is muted.

Sys#6 Sys#7

Sys#8 Sys#9Pic 7 Internal interferences test at Asam-asam via Spectrum Analyzer

External InterferencesOn this test, we observe the response of spectrum analyzer for each frequency channel band width when the TX on all system at Asam-asam are muted.

Sys#6 Sys#7

Sys#8 Sys#9Pic 8 External interferences test at Asam-asam via Spectrum Analyzer

There was noise captured on spectrum analyzer response when the RX Sys#9 at Asam-asam is observed, the noise is located on upper space bandwidth. The working frequency/ center frequency of this channel is

Interference

Interference

4670MHz, so the frequency area which should free form interference for this channel is from 4630 MHz to 4710MHz or 80MHz, here is the complete capture of spectrum analyzer response for this channel

Pic 9 Spectrum Analyzer responses of RX sys#9 at Asam-asam

The Spectrum Analyzer screen capture above shown there was noise captured on upper space bandwidth of RX sys#9, to figure the source of that noise, NEC team observe the Spectrum Analyzer response by widen the observation area, the result are shown below

Pic 10 Spectrum Analyzer responses of RX sys#9 at Asam-asam

Working Bandwidth

Lower Space Bandwidth

Upper Space Bandwidth

Center frequency 4670MHz Interferenc

e

Receive signal sys#9

Center frequency 4670MHz

Noise

The observation result is shown the noise which interfere RX sys#9 is from 4690 MHz to 4750MHz, which is bandwidth of TX sys#6 of radio Asam-asam it selves. For more detail about frequency channel assignment of these radio please refer to capture below

To ensure that the interferences come from TX sys#6, NEC team observe the Spectrum Analyzer responses of RX sys#9 while the TX sys#6 is muted, the result the noise is clear, see capture below for more detail

Pic 11 Spectrum Analyzer responses of RX sys#9 at Asam-asam

Receive signal sys#9 Noise

clear

The capture above proves that the source of noise/ interference is come from TX sys#6 radio Asam-asam it selves, this phenomenon is called PIM (Passive Inter Modulation) which is can be caused by: Contaminated contact (dirt, dust, moisture or oxidation) Loose contact (transportation, shock, vibration, or installation)

D. Action

1. Check the connection quality between TRP and BRCKT

NEC team done the inspection of connection quality between TRP and BRCKT and tighten the improper connection to solve the PIM effect, but the problem is still occurred.There are some items which have to be check related to this phenomenon: Termination/ feeder connector installation quality Feeder quality (VSWR, Return loss, etc) Quality of duplexer CKT

D. Conclusion

There was external interference on sys#1 at Jorong There was PIM effect on sys#9 Asam-asam The transmission quality is degraded due to fading, interferences and

PIM