GMR1000 vs GMR5000 vs GMR6000: which GMR master clock suits my network?
Masterclock offers three GMR grandmasters: the compact GMR1000, the expandable GMR5000 and the substation-grade GMR6000. They share the same NTP and time code architecture, but differ in PTP capability, holdover options, power supply and network redundancy. Below you will find a factual comparison based on the current datasheets so you can make the right choice for your network.
Quick recommendation
- Choose the GMR1000 if you need a compact NTP server with optional time code output for networks up to a few dozen clients, with DC power available on site.
- Choose the GMR5000 if you are looking for a 1U rackmount grandmaster with dual-port NTP, expandable with OCXO or Rubidium holdover, IEEE 1588 PTP and full time code I/O. This is the default choice for broadcast and mid-sized networks.
- Choose the GMR6000 if you need PTP IEEE 1588-2019 with IEC 61850-9-3 Power Profile, dual 10 GbE optical, hardware-redundant power and AES256 SSH, the grandmaster of choice for digital substations and critical data centres.
Specifications side by side
| Feature | GMR1000 | GMR5000 | GMR6000 |
|---|---|---|---|
| PTP IEEE 1588 | Option | Option | Standard (IEEE 1588-2019) |
| IEC 61850-9-3 Power Profile | No | No | Yes |
| NTP ports | 1× RJ45 10/100 Mb | 2× RJ45 10/100 Mb (dual-port) | 4× 1 GbE + 2× SFP+ 10 GbE optical |
| GNSS receiver | GPS or GPS/GLONASS (option) | GPS or GPS/GLONASS (option) | Multi-GNSS: GPS, GLONASS, Galileo, BeiDou, QZSS |
| Standard oscillator | TCXO ± 3 sec/year | TCXO ± 3 sec/year | FAST disciplining + Low Phase Noise |
| Holdover options | OCXO ± 0.25 sec/year | OCXO or Rubidium | OCXO (standard), Rubidium for multi-day holdover |
| Time code I/O (IRIG-B / SMPTE) | Optional | Optional | Optional |
| Power supply | DC 9-28 VDC + external 12 VDC adapter | Universal AC | Dual AC or DC (hardware-redundant) |
| Form factor | Compact: 16.4 × 10.3 × 3.7 cm, 454 g | 1U rackmount: 48 × 4.4 × 13.1 cm, 1.2 kg | 1U rackmount (see datasheet) |
| Display | Optional 6-digit | 13-digit (date/time or day-of-year) | Web interface |
| Security | Telnet or SSH, SNMP custom MIB, IPv4/IPv6 | Telnet or SSH, SNMP custom MIB, IPv4/IPv6 | AES256 SSH encryption + MD5 authentication |
| Conformity | FCC, CE, RoHS, ANSI | FCC, CE, RoHS, ANSI | IEC 61850-9-3, IEEE C37.238, FCC, CE, RoHS |
| Warranty | 5-year limited parts & labor | 5-year limited parts & labor | 5-year limited parts & labor |
When to choose each model?
GMR1000, compact multifunctional master clock
The GMR1000 is intended for installations where space is limited and where a single NTP server is enough. With an external 12 VDC supply and an enclosure of approximately 16 cm wide, it fits in narrow racks, on DIN rail (optional) or on a shelf in a technical room. As standard it includes NTP client + server, NMEA 0183, NENA and a TCXO oscillator. With the right options it grows into a time code generator (IRIG-B0 or B1, SMPTE 12M/309M) or PTP source.
In practice the GMR1000 is chosen by universities and smaller campus installations, for example as entry-level grandmaster for research or demo setups, and by organisations that need to serve a handful of NTP clients with optional IRIG-B output. For larger NTP volumes or where redundant power is required, you move on to the GMR5000 or GMR6000.
GMR5000, expandable 1U rackmount grandmaster
The GMR5000 is the workhorse grandmaster in the Masterclock range. The 1U form factor fits in any standard 19" rack. Dual-port NTP (two independent 10/100 Mb Ethernet connections), 13-digit display, Kinemetrics/Truetime serial protocol and full time code I/O (IRIG-B0 or B1, IRIG-A0/A1, IRIG-E0/E1, SMPTE 12M/309M, 24/25/30 fps and 29.97 drop frame) make it suitable for broadcast, industrial control and mid-sized IT networks.
The GMR5000 is chosen when an organisation grows beyond what an NTP100 time server can serve, or when time code generation is needed alongside NTP. A typical profile is a broadcast environment with genlock / black burst requirements alongside NTP for the IT infrastructure, or an industrial customer that has to feed NTP clients and distribute IRIG-B to a TCDS display and distribution amplifiers (DA12 / DA232 / TCA100) at the same time.
GMR6000, substation-grade PTP grandmaster
The GMR6000 is the flagship: a PTP IEEE 1588-2019 Grandmaster with IEC 61850-9-3 Power Profile and IEEE C37.238 conformity. Four 1 GbE ports plus two SFP+ 10 GbE optical ports, FAST disciplining technology and hardware-redundant power (dual AC or DC) position it for digital substations, critical data centres and networks where sub-microsecond accuracy and no single point of failure are crucial. AES256 SSH encryption and MD5 authentication round out the security profile.
Multi-GNSS (GPS, GLONASS, Galileo, BeiDou, QZSS) ensures the GMR6000 is not dependent on a single satellite constellation. Optional Rubidium holdover bridges days without GNSS, relevant in power substations or indoor industrial sites where antenna view is not guaranteed. The GMR6000 is requested by utilities, broadcast organisations with PTP-AVB requirements and research institutes that need to demonstrate IEC 61850 conformity.
Frequently asked questions
Do I need a GMR grandmaster, or is an NTP100 time server enough?
Below approximately 50 NTP clients in a simple network, an NTP100-GNSS or NTP100-OSC is enough. From around 50 clients with mixed NTP traffic, or when you want to generate or distribute IRIG-B time code to displays, you choose a GMR grandmaster. For PTP (IEEE 1588) a GMR is required anyway.
Can the GMR1000 do PTP?
IEEE 1588 Precision Time Protocol is on the option list for the GMR1000. For PTP applications that require hardware timestamping at switch level (sub-microsecond accuracy) we recommend the GMR5000 or GMR6000. In practice the GMR1000 is the smallest model and is deployed mainly as NTP server plus time code generator.
What is the difference between OCXO and Rubidium holdover?
Both oscillator options preserve time during loss of the GNSS signal. OCXO holds approximately ± 250 ms/year (around 1 ppb/day) and is suitable for hours to a maximum of one day of holdover. Rubidium holds several orders of magnitude more accurately and is chosen for multi-day holdover in critical infrastructure. Rubidium is available only on the GMR5000 and the GMR6000.
Does the GMR6000 support the Power Profile for digital substations?
Yes. The GMR6000 is a PTP IEEE 1588-2019 Grandmaster with IEC 61850-9-3 Power Profile and is explicitly positioned for digital substations. The GMR5000 supports IEEE 1588 but without Power Profile conformity. For IEC 61850 environments the GMR6000 is the appropriate choice.
What power supply does each GMR offer?
The GMR1000 operates on DC 9-28 VDC with an external 12 VDC adapter. The GMR5000 has a universal AC input. The GMR6000 offers hardware-redundant power (dual AC or DC), essential for data centre and substation installations where power loss is not an option.
Not sure? Daylight bv has been authorised Masterclock distributor since 2014. We are happy to help you choose based on clients, network topology and holdover requirements.
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