• Stephen Biss

Reliability: 5000 64- in 2011- RFI

This is the same Intoxilyzer® 5000 64- series machine depicted in the June 16 and June 17, 2015 blog entries. These videos were uploaded to YouTube in 2011.The instrument appears to be operating normally with subject test results in the 120 to 130 range. The cal check system seems to be working properly with good results. The problem with these tests, in good agreement, is that the test subject, me, had zero BAC, as demonstrated in the sequence without RFI. This instrument has not received proper maintenance for many years. I apologize for the poor lighting on all of these videos.

The immediate cause of the errors is received-text-message-RFI. The Nokia mobile phone used to receive the texts uses several frequencies, one of which is about 850 mhz. To the best of my knowledge, the original 5000 and 5000C RFI systems were designed to inhibit RFI up to about 600 mhz - where police radios operated during 5000/5000C product development.

One would expect that the automatic systems would preclude such an RFI effect. Unfortunately they don't always work and unfortunately police officers don't always follow the ATC rule about no radio transmissions in the breath room.

The absence of an RFI flag does NOT preclude the real possibility of RFI compromising reliabilty of a cal. check or a subject test if police are using a mobile phone in the breath room.

Dicussion: What are the possible causes of the problem? What do we need to know to both identify that there was an error (not apparent from the test records) and the possible contributing factors. I suggest the following pieces of information are necessary to an informed opinion:

1. The history of the machine i.e. not properly maintained and perhaps the Faraday cage (the steel cover and mesh shielding) has been opened once-to-often and not put back together properly. Perhaps someone who was not properly trained and not working in a factory authorized service centre serviced the machine. What does the maintenance log say? Perhaps there are gaps in the RFI shielding on this particular machine on this date. Perhaps the RFI crept in through an air vent or other opening that was not put back together properly. What do anecdotal notes say?

2. There is a source of RFI in the room. You can't always count on automatic systems. If there is a protocol designed to CONTROL such error it needs to be adhered to. The defence needs to know if a mobile phone was used in the breath room and the particulars of the phone and its use.

3. Has the hardware/software in this particular instrument been upgraded to deal with more modern technology and frequencies, that were not in existence when the instrument was being developed? It is my understanding that the manufacturer released an RFI system upgrade at some point in 5000C use. Doesn't the defence need to know if a particular instrument's hardware and software have been upgraded?

The following is a related experiment running a series of cal checks on the same machine. Notice that on one occasion the RFI produced a cal check result of 128 mg/100 mls rather than the expected 100 and on another cal check sequence produced a result of 100 but "interferent subtracted". There was no "RFI Inhibit" flag.

The following is yet another cal. check RFI experiment using the same instrument. This video was uploaded to YouTube in 2011. It is not just subject tests that can be affected by RFI. Cal. checks can also be affected by RFI. Please remember that in order for the approved instrument analysis of subject tests to be reliable, the cal. checks need to be reliable. These cal. checks are made meaningless by the application of RFI produced by a receiving mobile phone. If call checks are meaningless ,the breath tech should not be using the approved instrument in testing the subject. If a breath tech is using a cell phone (sending or receiving - including passively) in the breath room then cal. checks are not reliable. The fact that several cal. checks were in the 100 range does not preclude the possibility that RFI was interfering with those cal. checks and producing a false result close to the target. Cal. checks check the Intoxilyzer calibration, not the other way around. The Intoxilyzer® results of a cal. check cannot be used to establish the reliability of the cal. checks. Cal. checks need to be conducted in a breath room that is free of RFI. Police officers need to stop using mobile phones in breath rooms.

WARNING: These videos and what you read at this blog cannot be used in Court. They are NOT EVIDENCE. They are merely here for discussion among defence lawyers. The author is not an expert. You need to consult and retain an expert witness if you want opinion evidence to be used in Court. Please do not attempt to file this page or these videos with any Court. They are for discussion only. This author is not an expert.

#reliability #rfi

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