The Philips high performance timer/counters PH 6652, PM 6654, PM 6652C and PM 6654C are fully programmable and satisfy most frequency and time measurement requirements. The four instruments look the same; the differences being found in resolution, accuracy and measuring speed. The PM 6652 and PM 6652C have a 10 MHz (100 ns) clock frequency, whereas the extra high resolution PM 6654 and PM 6654C features a 500 MHz (2 ns) real time clock. Thanks to their short measuring cycle times, the PM 6654 and PM6654C are particularly well suited to high speed automatic test systems. The 'C'-version, introduced in 1986, have new features added to those of the original PM 6652 and PM 6654. A note is made if a function described in this manual is not applicable to the original PM 6652,-54. All units are also available in blind panel versions. Choice of crystal oscillators The choice of crystal oscillators ranges from a standard oscillator to the 5 x 10"“^/24 h oven stabilized oscillator PM 9691. The high stability crystal oscillators are available as options for later upgrading of the counters. High measuring power The two timer/counters feature 14 different measuring modes: everything found in conventional counters, plus extra functions such as: PHASE, (directly in degrees), RISE/FALL TIME, DUTY FACTOR and VOLT. FREQUENCY and PERIOD measurements are made very rapidly. The PM 6654 needs only one second for a 9 digit resolution while the PM 6652, in the same time, gives 7 digits. Both models perform measurements such as burst frequency, multiple burst frequency average and externally gated frequency measurements. Trigger HOLD-OFF can be activated in frequency and period modes. It inhibits stop triggering during an adjustable hold-off time after start of the measurement, to avoid false triggering due to noises or interference (e.g. relay bounce). Mathematics The mathematic facilities of scaling and/or offsetting the measuring result extends the application possibilities. Some examples; - Vpp measurements can be converted to Vrms* - Frequency readings from a transducer can be calibrated as RPM. - Liters/s, gallons/min or m/s. - Phase measurements can be converted from degrees to dians. Time interval measuring accuracy The PM 6654 with 2ns single shot resolution allows time interval measurements with a very high accuracy and resolution. Averaging a large number of measuring results in time interval, pulse width or rise or fall time modes gives a resolution of less than one picosecond with the PM 6654 and down to 10ps with the PM 6652. Trigger accuracy The PM 6652/54 inputs feature 1ns rise times and 20mV sensitivity over a -5V...+5V range. The counter can simultaneously display the set trigger levels of both the A and 8 channels. What appears on the display are the real trigger points. Automatic hysteresis compensation enables triggering at the set trigger level. Systematic trigger errors are thus kept to an extremely low level. The PM 6652/54 gives full control over defining start and stop triggering. Arming and trigger hold-off enable rejection of unwanted signals which would otherwise trigger the counter. Simple programming of IEEE-488 bus performance The PM 6652/6654 are fully programmable, including all trigger controls. The optional interface card PM 9696 allows bus operations at a low additional cost. The resolution and measuring speed of the PM 6652/54 can be fully exploited by using the hiqh speed dump mode, allowing up to 400...500 measurements per second. The IEEE 728/IEC-625-2 code and format norms are fully implemented in these counters. The PM 6652/6654 can write their own program messages. First one finds the best control settings for a measurement. Thereafter activate the BUS LEARN mode, and the counter sends the status of all manually set controls to the controller. This eliminates the risk of programming errors and the need for debugging. The eight ''stored panel programs" P1...P8 can also be selected and created via the bus. This requires only one message and greatly reduces the bus communication load.