Last night we saw John Softley's Just the Job Dixieland Jazz band at The Epsom Playhouse
Tuesday jazz club. All the band members were great musicians but I would particulary like to thank John Softley for his great banjo and guitar playing. The best band yet !
Yesterday evening we had dinner at the Preston Cross hotel
. We had not been there for 10 years and the food and wine was as good as ever, with friendly service. There is Jazz on Sunday afternoons !
Yesterday I used the new Tektronix TDS 1002 to test a prototype 3 phase converter
. It is cheap, small, light, and at 1 Gsample/s and 8 bit resolution should be well clear of frequencies that might cause aliasing. I realised that the higher resolution and lower sampling rate of the TiePie made aliasing of low amplitude high frequencies quite likely. We will live with 8 bits; although it is barely sufficient, we can cross check the essential measurements with other instruments.
Although the CRO is cheap, all the accessories are very expensive, e.g. the (essential for us) x100 probes are 200 GBP compared with 40 GBP from RS. We are trying to manage without differential probes for now by either using both probes into a single reading or by floating the 'scope (plastic case so not dangerous unless you touch the BNC connectors in the 'hot' condition).
For current measurements we hope to use the CTs from our true RMS wattmeter. I need to buy precision 1 ohm load resistors for them.
Yesterday I ordered the new oscilloscope. We chose the Tektronix TDS 1002 as the lowest cost 1Gsample/s digital storage instrument. This high sampling rate should make it easy to design an anti-aliasing filter for to reduce unwanted frequencies down to below the 8 bit resolution.
A telephone caller asked "what does Isomatic do ?" How does one explain in a few words ? I pointed her to our Table of Contents
Just back to deal with 2117 E-mails and a pile of post ! Oban was a great choice of location and the hotel was the best choice in Oban. Stunning views, great food and good service.
This is the last post for a week as we shall be on holiday in Oban, Scotland, staying at The manor House hotel
Yesterday evening we went to a concert given by the LSO Chamber Orchestra at The Barbican.
Five concertos were played, featuring violins, cello, double base, trumpets and bassoon.
The subject of aliasing has arisen in discussion regarding digital oscilloscopes. Shannon/Nyquist is OK in theory but in practice sampling a sine wave at twice its frequency produces a straignt line, i.e. zero frequency. It is necessary to sample at 5 to 6 times the frequency.