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DMM EEVblog 121GW (FW 2.0.5): Wrong period time ("ms") measurement?

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RK_aus_S:
Hi

Rather accidently, I noticed that my EEVblgo 121GW, FW 2.0.5 shows a wrong period time ("ms" milliseconds), for example when mains voltage is applied (here in Switzerland 230 V / 50 Hz). The 121GW shows 10 ms - but should display 20 ms (if I understand the function perdiod time right).

So I gradually downgraded the firmware and can confirm, that with FW 2.0.2 the period time is correct 20 ms. From FW 2.0.4 on the perdiod time is wrong with 10 ms.

Can anybody confirm - or disprove - my observations?

Kind regards
Roman

armandine2:
Reply removed - after getting the OPs point

bicycleguy:
The ms is the on time of a signal as shown with this 25% duty cycle 50Hz.

The manual says:
1. Frequency
2. Pulse width
3. Duty cycle

bdunham7:
Whether 20ms or 10ms is the 'correct' reading for a 50Hz sine wave depends on whether the measurement is intended to be 'period' or 'pulsewidth'.  Typically a DMM will display pulsewidth not period, as the period can be easily inferred from the frequency reading.  On p. 48 of the manual it states that it is intended to be pulsewidth, so 10ms would be correct.  It appears that they got that wrong with earlier versions and corrected it, not the other way around. 

https://www.eevblog.com/wp-content/uploads/2017/11/121GW-Manual-5.pdf

joeqsmith:
The first manual I have shows Period rather than Pulsewidth. 
***
Make that the first several manuals show Period but they start to mix in Pulsewidth.  Maybe they couldn't decide what they wanted. 

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