System Overview

The system consists of an antenna, analogue frontend, digitising and digital processing hardware and software to analyse and calibrate the system.

Specifications and requirements

• Simple
  • Carel: Agree
• Covers frequency range for KAT7
  • Carel: See comments below
• Flexible and upgradable for more bandwidth, different frequency bands etc
• Able to run off a battery for a few hours
  • Carel : yes please, but beware of RFI from invertors
• Portable - able to fit in the back of a bakkie
  • Carel: yes please
• Limit self-induced RFI
  • Carel: At least it should be stable and known
• Able to log data to disk
  • Carel: yes please
• Realtime display of spectral output
  • Carel: we just need a quick look view to make sure the measurement went OK, detail display can be done on laptop afterwards
• Antenna and amplifier
  • Carel: Various antennas (due to frequency ranges)
  • Carel: Integrated amplifier required (in RF box or better at Antenna)
  • Francois: Noise diode?

Issues and questions

By Carel:

I have the following requirements / uses for such a system:

• Formal qualification on site of all the Ancillary equipment that I am introducing to the site (permanent items)
• Ancillary equipment is typical electrical and commercial electronic equipment
• Monitoring all electrical / electronic equipment during construction , to ensure they are ll removed after construction
• Special investiagions as requested by Bruce / Adrian / Pieter (example is the current electric fence saga)

At present I use the following procedure:

• The equipment under test is switced on and off (to figure out what RFI is from the EUT and what is from other ewuipment / environment)
• The first test is normlly done with a current clamp (i.e. conducted RFI) - this give the frequencies , if not accurate levels
• Once the frequencies are known, a suitable antenna is selected and radiated RFI is measured

Antennas available on site:

• LPDA (300MHz to 6 GHz) - nice and portable , need a bit of gain
• Number of dipoles (5% frequency bands around centre frequency), we have a set adjustable from 25 Mhz to 2 GHz
• Monopole (loan from MESA) - 25 MHz to 280 MHz
• RFI system 3 is still standing on site and we can consider canibilsing it
• We can procure additional antennas

In terms of frequencies:

• We cannot just work with KAT-7
• PAPER is already on site (100 MHz to 200MHz)
• C-BASS is going live early next year (around 5 GHz)
• The site must also be clean for meerKAT, so we need to test for that frequency range as well

Antenna / Antenna interface

Portable packaging

RF Analogue hardware

Digital hardware

Capturing software and realtime monitoring

System Engineering & Project Management

• By Carel:
  • I will put the structure of the system as well as all documents into RAMLOG and publish on web on a ongoing basis
  • In terms of testing we should do at least:
    • Test in Lab
    • Test in field (even without the final packaging) to evaluate usability
  • Dates
    • be ready to use this in action for MeerKAT Infrastructure acceptance by Late 2011