Vremya-ch VCH-315M User manual


V R E M Y A –C H
Joint Stock Company
MULTICHANNEL FREQUENCY COMPARATOR
VCH-315M
Operation Manual
411146.039OM
Osharskaya str., 67, Nizhny Novgorod, 603105, Russia
tel./ fax [phone], http://www.vremya-ch.com
Инв. № подл.
Подп. и дата
Взам. инв.№
Инв. № дубл.
Подп. и дата

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Table of contents
1List of abbreviations........................................................................................ 3
2Safety precaution............................................................................................. 4
3Device description........................................................................................... 5
3.1 Description and operation...................................................................... 5
3.2 Key applications..................................................................................... 5
3.3 Product composition ..............................................................................7
3.4 Product specifications ............................................................................8
3.5 Basic configuration and operation .......................................................11
4Operating procedure...................................................................................... 15
4.1 Safety requirements..............................................................................15
4.2 Location of control and connection systems........................................15
4.3 Preparing the device for use................................................................. 17
4.4 Operating procedure.............................................................................21
4.5 Measurement modes ............................................................................22
5Troubleshooting ............................................................................................ 34

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1List of abbreviations
ADEV –Allan deviation
PC –personal computer
RS232 –serial port
Multichannel frequency Comparator VCH-315M –device

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2Safety precaution
2.1 Carefully read the operating manual before working with the device and note the
safety information.
2.2 Accessible conductive parts of the device are protected by basic insulation and
electrically connected to the protective grounding.
2.3 The device is grounded via protective conductor in the power cable and
protective earth terminal marked on the rear panel.
2.4 The device is connected to the AC via three-wire power cable (two poles and
ground) included in the device kit.
2.5 To avoid the influence of static electricity all further connections must be made
only with the grounded device.
2.6 You must avoid contact with current-carrying parts during repair as it may result
in shock.
2.7 Before touching any components or wiring always unplug the device.
2.8 All repair and maintenance of the device must be carried out by qualified
personnel authorized for work on high voltage (up to 1000V).
2.9 RS-232 interface cable should be connected only when the the device is turned
off. Failure to do so may result in damage to the interface.

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3Device description
3.1 Description and operation
Multichannel frequency comparator VCH-315M is intended for simultaneous
frequency instability measurements of a group of sinusoidal signals 5, 10, 100 MHz.
Device can be managed and measurement results can be displayed and stored
using a PC and special software. Monitored parameters and control commands are
transferred via RS-232 interface, USB or local area network –LAN.
The external view of the device is given in Fig. 1.
3.2 Key applications
The main applications of the device:
−crystal and quantum frequency standards production and checking;
−scientific research.
−in metrology as an integral part of the storage systems;
−as an integral part of automated measurement systems. Built-in RS-232,
USB and LAN interfaces provide remote measurement of the monitored
signals frequency instability characteristics.

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Figure 1 –External view of the device

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3.3 Product composition
The device composition is given in Table 1.
Table 1 –Device composition
№
Model and designation
Quantity
1.
Multichannel frequency comparator VCH-315M
1
2.
Fuse 3,15 A
6
3.
Power connecting cord
1
4.
Interface RS-232 cable 685622.003
1
5.
Interface cable USB 2.0 AM/BM-1.8M
1
6.
Power splitter ZFSC-2-1W-S+
2
7.
RF interconnecting cable 685670.372
4
8.
RF interconnecting cable 685670.376
2
9.
Multichannel frequency comparator VCH-315M
Installation disc
1
10.
Multichannel frequency comparator VCH-315M
Operating Manual
1
11.
Multichannel frequency comparator VCH-315M
User guide
1

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3.4 Product specifications
3.4.1 The device is managed and measurement results are displayed and stored using a
PC. Monitored parameters and control commands are transferred via RS-232
interface, USB or LAN. The PC must meet the following minimum
requirements:
−Processor: Intel Pentium-IV 2 GHz or similar;
−Operating system: Microsoft WindowsTM XP, Vista, 7, 8, 10;
−RAM: 512 MB.
3.4.2 Input signal parameters:
−nominal frequencies –5; 10; 100 MHz;
−RMS voltage: (1,0±0,2) V at (50±1) Ohm;
−relative frequency difference: –5,0×10−9 to +5,0×10−9.
3.4.3 Number of measuring channels: 8 (eight modules with two inputs for the
measured signals ("fх", "fy").
3.4.4 Averaging time range,  : from 1 s up to 1 day.
3.4.5 Noise passband: 3 Hz.
3.4.6 Warm-up time:
−2 h, for averaging time range not more 100 s;
−6 h, for averaging time range >100 s.

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3.4.7 Frequency instability introduced by device –Allan deviation (at zero frequency
difference between input signals and temperature deviation not more than
±1,0 °С per hour within the operating temperature range), is displayed in the
Table 2.
Table 2 –Frequency instability, introduced by device
Averaging
time, 
Frequency instability introduced
by Multichannel frequency comparator VCH-315M
“One-channel” mode,
ADEV
“Two-channels” mode,
cross-ADEV
1 s
6.0×10–14
2.0×10–14
10 s
2.0×10–14
3.0×10–15
100 s
3.0×10–15
1.0×10–15
1 h and more
3.0×10–16
2.0×10–16
Note: frequency instability introduced by the comparator is guaranteed after
warm-up time (according to s. 3.4.6).
3.4.8 The device provides continuous non-stop operation in working conditions with
all specifications preserved.
3.4.9 Power supply voltage:
−AC power supply: (22022) V, (50±1) Hz;
−DC power supply: (22 –30) V.
3.4.10 In the absence of AC voltage the device automatically switches to backup
power from an external DC source. The device will retain its specifications
during the AC/DC change-over.

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3.4.11 Power consumption:
−AC power supply: not more 40 VA;
−DC power supply: not more 35 W.
3.4.12 Ambient temperature:
−operating: +5 to +40 °С,
−non-operating: –50 to +50 °С.
3.4.13 Weight: no more than 12 kg net; 16 kg in factory package.
3.4.14 Dimensions: 133483325 mm.

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3.5 Basic configuration and operation
3.5.1 Principle of operation
Device operation is based on phase-time method: information about the phase
difference of the input signals is converted into time intervals that are measured by a
digital time interval meter. Then the processor transfers these measurements to the
computer where all the data is processed by a special program that gives the
characteristics of the input signals instability in digital and graphical forms.
3.5.2 Description of the circuit diagram
Circuit diagram illustrating the operating principle of the device is shown in
Figure 2
The device consists of these main parts:
−eight identical frequency comparators (channels);
−processor;
−signal and power bus;
−indication signal driver;
−group of front panel indicators;
−power supply.

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Figure 2 –Circuit diagram
The frequency comparators measure the increment of the phase difference
between the signals at the fx and fy inputs and feed the measured data to the processor.
Noise passband of 1 Hz is generated by digital filtering.
The processor receives the data from the frequency comparators, processes it,
transmits to the PC and manages the operation of the frequency comparators by
commands from the special program, and also controls the indicators. Transmission of
measurement data to the computer and reception of control commands is carried out by
the processor via RS-232, USB or LAN interfaces.
Tested signals
5; 10;100 MHz
SIGNALS AND POWER BUS
INDICATION SIGNAL DRIVER
fy fx
FREQUENCY
COMPARATOR 1
(CHANNEL 1)
tyx
fy fx
FREQUENCY
COMPARATOR 8
(CHANNEL 8)
tyx
Interfaces
RS-232 USB LAN
RS-232 USB LAN
PROCESSOR
POWER
SUPPLY
DC ±12 V,
+5 V, +3.3 V
220 V 50 Hz
22…30 V
Supply voltage
AC DC
GROUP OF FRONT PANEL INDICATORS

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The power supply unit generates stabilized voltages (± 12 V, 5 V, 3.3 V) needed
to power the device units from the 220 V AC. It also switches to backup DC power
source with (22–30) V voltage.
The power supply unit has a AC 220 V indicator ("POWER"), an external DC
(22–30) V power supply indicator ("22 ... 30 V, 35 W") indicator and a power
supply unit normal operation indicator ("NORM") which shows the presence of all
output stabilized voltages of the power module.
The front panel group of indicators shows simultaneous presence of signals on
the inputs "fx", "fy" for each of the eight frequency comparators
("CHANNEL 1" - "CHANNEL 8"). The indicators are green LEDs turning on and off
at a frequency of about 1 Hz. The front panel also contains the AC 220 V power
indicator and the external DC source indicator.
Indication signal driver generates indication signals and sends them to the front
panel indicators by the processor command.
Power supply and internal information exchange between the device units are
carried out via the signals and power bus. The device units are connected to it in
parallel through the connecting plugs.
3.5.3 Remote control and monitoring
The device is controlled from PC using the special program via RS-232
interface, USB or LAN (Windows only).
The following functions are implemented in the program:
−receiving and automatic saving of measurement data from the comparator;
−calculation of statistical functions characterizing the frequency difference
between two signals;

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−display of measurement results and calculated functions in charts on the
screen;
−printing charts on a printer connected to the computer.
The program for processing measurement data of frequency
comparators/counters "Analyzer" is included with the program for control of
multichannel frequency comparator VCH-315M. It provides the following
functions:
−simultaneous processing of the data across multiple channels of the
comparator, and the simultaneous processing of the data from several
comparators (maximum number of concurrent entries –32);
−processing of the previous measurements, and processing of the current
measurement data with automatic update of charts and statistical
characteristics;
−a wide range of computed parameters (mean relative frequency difference
and frequency drift by least-squares method, standard deviation, Allan
deviation, Hadamard deviation, maximum time interval error, time
interval deviation, power spectral density of phase and frequency noise);
−calculation of the statistical characteristics with overlap method;
−elimination of the frequency drift;
−the cross-correlation processing that allows to reduce the noise level
contribution of the comparator in the measurement of the frequency
instability (with appropriate measurement scheme);
−the cross-correlation processing that allows to evaluate the characteristics
of the frequency instability not only for pairs of signals, but also for each
signal individually by the method of three oscillators.

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4Operating procedure
4.1 Safety requirements
Accessible conductive parts of the device are protected by basic insulation and
electrically connected to the protective grounding
The device must be grounded before use via protective conductor in the power
cable and protective earth terminal marked on the rear panel
ATTENTION! Grounding failure makes the device unsafe. Operation of the
ungrounded device is prohibited.
The device is connected to the AC via three-wire power cable (two poles and
ground) included in the device composition.
ATTENTION! Usage of any other power plugs is STRICTLY
PROHIBITED.
Operation of the device must comply with the electrical safety regulations in
force at the operating facility.
4.2 Location of control and connection systems
Connectors, indicators and control elements on the front and rear panels of the
device, are shown in Figure 3.
The purpose of connectors, indicators and control elements on the front and rear
panels of the device and their default states are given in Table 3.

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Figure 3 –Connectors, indicators and control elements on the front and rear panels

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Table 3 –Connectors, indicators and control elements on the front and rear panels
No.
Designation
Usage
1
POWER
AC power indicator
2
BATTERY
DC power indicator
3
CHANNELS
Channel indicators
4
fx, fy
Inputs for measured signals
5
RS-232
Serial RS-232
6
USB
USB interface
7
LAN
LAN interface (Ethernet)
8
POWER
AC power switch, AC power indicator
9
220 V 50 Нz 40 V·A
AC power socket
10
22…32V 35 W
DC power socket, DC power indicator
11
F 3,15 A L 250 V
Protective fuse
12
NORM
Normal operation indicator of the power
supply unit
13

Ground terminal
4.3 Preparing the device for use.
4.3.1 Operational limitations
It is recommended to place the device in a thermostabilized room with limited
access to personnel. The place for the device should be chosen taking into account the
dimensions of the device 133×483×325 mm and the need for free convection of air
through the ventilation openings of the device casing.
Warning! Do not place the device near any engines, generators, transformers, or
other equipment that may create magnetic fields and acoustic vibrations. Placement
near such equipment may impair the performance of the device.
Power supply voltage:

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−AC power supply: (100 –240) V, 50 or 60 Hz;
−DC power supply: (22 –30) V.
Ambient operating temperature: +5 to +40 °С,
Temperature deviation not more than ±1,0 °С per hour.
Device preserves its specifications after exposure to utmost conditions provided
6-hour warm-up time in normal operating conditions.
RS-232 interface cable should be connected only whet the device is turned off.
Warning! Failure to do so may result in damage to the device interface.
4.3.2 Preparation for measurements
Carefully read this operating manual before starting. Note the location of the
controls and connections (Figure 3) for their purpose (Table 3).
Ensure reliable grounding of the device. The protective grounding terminal
should be connected to the grounding conductor before other connections. The
fasteners of the ground terminal and the conductors must be securely fixed.
While the power is off, connect the device to the computer in one of the
following ways:
−RS-232 socket of the device with one of the COM ports of the computer
using the RS-232 interface cable;
−USB socket of the device with one of the USB ports of the computer
using the USB interface cable;
−LAN interface with the local area network (Ethernet network) using a
cable with an 8P8S connector.

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Attention! Connecting the device to the COM port of the computer when the
power of the device is turned on can damage the RS-232 interface of the device's
processor.
Connect the power supply:
−from the AC power line (100 - 240) V, 50 or 60 Hz to socket "220 V, 50
Hz, 40 V·A"
−from the DC power supply: (22 –30) V to "22…30 V" (backup power
source).
Make sure that the "POWER", "NORM" and "22 ... 30 V 35 W" indicators on
the power module panel are lit.
The "22 ... 30 V" indicator on the power unit panel lights up only if there is a
DC voltage on the "22 ... 30 V 35 W" connector.
To connect an external power source use a power cable with a
2PMT14КПН4Г1В1 (2PM14-4TKQB2) type connector. Pin 1 of the connector must
be connected to the positive pole of the DC power supply, and pin 4 to the negative
pole of the power supply (see Figure 4).
Figure 4 –DC power connecting cord
4.3.3 Program installation

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Install the "Multichannel frequency comparator " program and the program for
processing measurements of frequency comparators following the instructions given in
the "Multichannel frequency comparator VCH-315M User Guide" and "Program for
processing measurement data of frequency comparators/counters "Analyser" User
Guide".
Before using the USB interface of the device install a PC driver that creates a
virtual serial port when connecting the comparator via the USB interface, following
the instructions in the "Multichannel frequency comparator VCH-315M. User guide".
To control the device via the Ethernet install the special software, following the
instructions in the "Multichannel frequency comparator VCH-315M. User guide".