Published by Jingzhun, the daily maintenance and implementation of the hospital network clock system (Master Clock)
Jingzhun, the daily maintenance and implementation of the network clock system (Master Clock) of the hospital
1. NTP network clock server satellite antenna
1. Question: How to identify the antenna is good bad?
Answer: Put the white mushroom head of the antenna outdoors, connect the BNC head at the end of the antenna feeder to the antenna interface on the backplane of the network clock server product, turn it on, and the LCD screen will display the number of received satellites after a few seconds. When the value greater than 0 is displayed, it will Indicates that the antenna can receive satellites and can be used normally and with confidence.
2. Question: If the antenna is not long enough, how to deal with it?
Answer: The length of the antenna cable is strictly designed according to the antenna gain, and it is not allowed to cut, extend, shorten or add joints privately, otherwise it will seriously affect the reception effect or even fail to receive the signal. Therefore, when ordering, measure the actual wiring length of the antenna in advance, and purchase an antenna that is suitable for the length of the site.
3. How to consider satellite antenna lightning protection?
Answer: Under normal circumstances, high-rise buildings will take lightning protection measures. The white mushroom head is erected on the roof/window side/terrace/balcony, etc., which will not exceed the highest lightning protection measures of the building. When the antenna is installed on the roof, it should be placed on the building. Within the lightning protection range of physical lightning rods, as long as the field of view is sufficient, the distance above the roof should be as small as possible. If you are still worried about lightning strikes, you can add a special antenna lightning arrester. The lightning arrester is installed between the network clock server host and the antenna, without affecting the satellite reception effect. Before the thunderstorm season comes, it is necessary to carefully check whether the lightning protection grounding system is in good condition.
4. How to install and fix the satellite antenna?
Answer: Our standard configuration will be equipped with mounting brackets, expansion screws and other accessories. The connection between the mounting bracket and the antenna is threaded. There are 3 fixing holes under the mounting bracket. Drill holes on the roof and fix them with expansion screws.
Friendly reminders when installing the antenna:
1. Install the antenna mushroom head on the antenna bracket and fix it on the top of the house or on the platform. Make sure that the antenna mushroom head has as large a field of view (360-degree sky) as possible without obstacles.
2. The antenna should try to avoid the blocking of the antenna beam by hillsides, woods, high-rise buildings, iron towers, high-voltage transmission lines, etc. There should be enough field of view in the direction of the main beam of the antenna, and there should be as wide a viewing angle as possible directly in front of the antenna. It is generally required that the antenna base point be used as a reference, and the included angle to the highest point of the obstacle be less than 10 degrees.
3. All antennas are standard configurations, and should not be cut or superimposed at will, otherwise the reception of satellites cannot be guaranteed.
4. Connect the antenna to the network clock server host to test the satellite receiving effect before laying, which saves a lot of trouble than laying the cable and then measuring the satellite receiving effect.
5. When the satellite cannot be received, change the antenna to several places to try the effect, so as to distinguish whether it is the problem of the antenna itself or the problem of the installation position of the antenna.
2. Network clock server synchronization product size and working power
1. What is the size and color of the device?
Answer: The device is a standard 1U or 2U, 19-inch rack-mounted device, and the color is black.
2. What is the working power of the equipment?
Answer: AC power supply: 220V±20% or 110V±20%, 47Hz～63Hz;
DC power supply: 220V±20% or 110V±20%; device power supply self-adaptive, power consumption: ≤20W.
3. What are the time synchronization methods of network clock server synchronization products?
Answer: 1. Pulse synchronization signal (hard time synchronization): The synchronization pulse of the clock device is output in the form of empty contact, TTL level, 422 level (differential), 24V/110V/220V active, and current loop.
2. Time message (soft time synchronization): The time synchronization device reads the serial output time information of the synchronous clock once per second through the serial port. Serial port information includes year, month, day, hour, minute, second, and other special content specified by the user, such as the number of GPS satellites received, alarm signals, etc.
3. IRIG-B: A serial time-interchange code applied to shooting ranges. A time information encoding standard proposed by the "Range Instrument Group" under the US Range Command Committee is now widely used.
4. NTP protocol: Network Time Protocol (NTP) is a protocol used to synchronize the computer time, it can make the computer synchronize its server or clock source (such as quartz clock, GPS, etc.), it can provide high Accurate time correction (less than 1 millisecond difference from standard on LAN, tens of milliseconds on WAN).
SNTP protocol: SNTP is the abbreviation of Simple Network Time Protocol, which is an important engineering method for realizing time synchronization on the Internet. The SNTP protocol adopts the client/server working mode. The server receives GPS signals or its own atomic clock as the system time reference. The client obtains accurate time information through regular access to the time service provided by the server, and adjusts its own system clock to reach the network. The purpose of time synchronization. The communication between the client and the server adopts the UDP protocol, and the port is 123.
5. DCF77 signal (Deutsche, long wave signal, Frankfurt, 77.5kHZ): German calibration signal (DCF77 for short): operated by Physikalisch-Technische Bundesanstalt (PTB), launched from the southeast of Frankfurt. The carrier frequency is 77.5 kHz, and the time information encoding adopts pulse width modulation.
4. How to adjust the time of the network terminal?
Answer: The network clock server product uses the received GPS Beidou information (serial port + 1PPS) as the time source, and synchronizes all computers, routers, switches, DVRs, intelligent controllers and other devices in the network through the NTP/SNTP protocol to realize network time service. Most operating systems have built-in NTP service, and you only need to do some settings. (The specific configuration can be obtained from our company and will not be described in detail here)