SR and SC Series NTP Servers Help and Support: LF Radio Troubleshooting Tips
Models that this article applies to:
SR Series: SR7110, SR9210, SR9750, SR9850, SR9860D with MSF or DCF-77 LF radio antenna.
SC Series: SC7105, SC9205, SC9705 with MSF or DCF-77 LF radio antenna.
Summary
Struggling to get a good LF radio signal ? Here’s a few tips and pointers on how to receive a good consistent LF radio signal.
Tips
The SR and SC series NTP servers can be supplied with either a MSF or DCF-77 LF radio receiver. The MSF transmitter broadcasts at 60KHz, while the DCF-77 transmitter broadcasts at 77.5KHz. Both transmissions broadcast accurate time and date information.
The MSF time and frequency transmitter is located in Cumbria, UK. It can generally be received throughout the British Isles and much of North-Western Europe. The DCF-77 transmitter is located in Frankfurt, Germany. It can generally be received throughout Central and Northern Europe.
The LF radio antenna that can be supplied with the SR and SC series NTP servers is a wound ferrite antenna. There are two versions – one tuned to 60KHz for MSF reception (Product code: SR-MXS-00) and one tuned to 77.5KHz for DCF-77 reception (Product code SR-DXS-00). The same installation rules apply to both models.
1. Ferrite antennas are unidirectional – which means that they have an ideal orientation. They should be installed in a horizontal plane at right-angles to the source of the transmission. See fig 1 and 2 below.
2. Metal structures act as Faraday cages and can block radio signals. Ensure that the antenna is not placed in a metal enclosure. Also, metal building frames and cladding can cause problems – in which case mount the antenna externally, ideally on a surface facing the transmitter.
3. The higher the antenna can be mounted, the less interference is generally received. If signal reception is poor, mount the antenna as high as possible.
4. The antennas are supplied with 5m of cable, terminated with a BNC connector. You can extend this cable using 50 ohm RG58 coax up to 100m.
5. There is a red/green LED on the radio receiver unit which flashes in tune to the broadcast. When a good signal is being received, the LED should flash at a consistently regular one pulse per second. If the LED flashes irregularly or is constantly red or green, poor signal reception is indicated.
6. The broadcast range of the MSF transmitter is 1000km, while the broadcast range of the DCF-77 transmitter is 1500km. However, if the antenna is located in a valley or if nearby high-ground is between the antenna and transmitter, reception can be difficult.
7. If the antenna is placed too near to electrically noise equipment, interference can lead to poor signal reception. Ensure the antenna is located well away from any sources of electromagnetic noise.
8. For externally mounted antennas, we recommend the fitting of a LF radio surge suppressor (product code: SPP-LF), to protect equipment against lightning and other electrical surges.
UK MSF Signal Reception
Fig 1. The MSF LF radio antenna should be installed in a horizontal plane at right-angles to the source of the transmitter located at Cumbria, UK. The shaded area indicates the approximate broadcast range of the MSF transmission.
European DCF-77 Signal Reception
Fig 2. The DCF-77 LF radio antenna should be installed in a horizontal plane at right-angles to the source of the transmitter located at Frankfurt, Germany. The shaded area indicates the approximate broadcast range of the DCF-77 transmission.
LF radio reception can be affected by many environmental factors – for many installations GPS can be a much better alternative. Providing a GPS antenna can be provided with a reasonably good view of the sky, a good signal lock can generally be received.
