I was one of the early pre-orders of NAUTILUS LIFELINE DIVER VHF (with GPS and DSC capabilities). I am an electrical engineer by profession and have worked on several industry-leading radio projects over the past 12 years with Qualcomm Inc. So, the first thing I wanted to know about NAUTILUS LIFELINE radio was its technical characteristics and performance tests.
When I first unpacked my LIFELINE and looked at it and held it in my hands, several things quickly slipped out to me.
The first thing I noticed was that the weight of LIFELINE was concentrated in a small form factor. It seemed to me that the object was too weak to be positively floating. Since the only time that LIFELINE could be used when a diver floats on the surface, the diver’s preference should be for Positively Smooth, so if the radio became unbound or escaped the diver, he would swim and the diver might hope to receive it.
But when you open the top cover of the LIFELINE to control the radio, it negatively charges and immediately dives if the diver loses his grip on it. On the surface, I want all my emergency equipment to float.
The second thing I noticed was that, unlike most portable VHF radios, there was no external antenna SMA connector, because the LIFELINE antenna was integrated with the transceiver circuit inside its case. This meant that the LIFELINE antenna could not be disconnected and pulled from the tube itself. Why is it important?
VHF signals are line-of-sight signals, which means that VHF signals can be blocked and distorted by any obstacles between your radio and any other VHF radio stations. Therefore, it is important to find a radio station antenna as high as possible above the surface of the water in order to get higher waves that will block your signal and help avoid distortion of the signal from the reflections of a multipath signal emerging from the surface of the water, which may interfere with your main signal.
The obvious way to do this is to add a low-level extension cable between the radiotelephone and the antenna and use your SMB as an antenna mast and thereby gain some height above the waves, and also expand your radio station's transmit and receive range. But without an external SMA antenna connection, there is no way to lift the NAUTILUS LIFELINE antenna, regardless of the radiotelephone itself.
NAUTILUS people know that the design of their product inherently limits the range of radio signals (see Specifications below), because in their Documentation of use for transmitting alert messages about distress they indicate “For maximum range, hold Lifeline as high as possible above the water line.” ,
What they do not tell you is that when the coast guard receives your DSC distress alert messages, your MMSI identifies your radio, and the coast guard immediately sends the command back to your radio, which will change it to VHF channel 16, so that they can "talk" with you. VHF channel 16 is also constantly monitored by all VHF radio stations, so everyone within your range of signals (i.e., potential rescuers) are emergency call listeners.
Thus, you will have to lower the LIFELINE from the length of your arm to your mouth, talk to the radio microphone, and this will limit the range of your signal and possibly make your emergency voice communication with the Coast Guard impossible. The ability to communicate by voice in the largest possible area is crucial to a successful rescue.
The following is a comparison of the NAUTILUS LIFELINE DIVER with another STANDARD HORIZON HX851 portable VHF radio, also with GPS and DSC capabilities.
A side-by-side comparison of the two manufacturers design specifications, performance benchmarks and some field test results are shown in the table below. I do not claim that this is a strict comparison, but it is more than enough to distinguish the performance of two radio stations.
Maximum transmit power
LIFELINE: 1.85 W
STANDARD HORIZON HX851: 6.00 W
Reception sensitivity
LIFELINE: Not specified in their user documentation.
STANDARD HORIZON HX851: 0.25 µV for 12 dB SINAD (benchmark for the best portable VHF radio)
(Note. Hours-long field testing side by side showed that the STANDARD HORIZON HX851 can explicitly receive VHF broadcasts that my NAUTILUS LIFELINE cannot.)
Antenna height above water
LIFELINE: The length of your arm
STANDARD HORIZON HX851: 5 feet using a low-loss antenna extension cable and SMB as an antenna mast
Signal range for voice
LIFELINE 4 to 5 miles (The field test results in the following independent review reduced this range to 2.5–3 miles. See the Scuba Gear Reports field.)
STANDARD HORIZON HX851: 8 miles
Signal range for DSC messages
LIFELINE: 8 miles
STANDARD HORIZON HX851: 20 km
Speaker Sound Power
LIFELINE 400 mW to 8 ohms with 10% THD
STANDARD HORIZON HX851: 700 mW to 16 ohms with 10% THD
He is swimming?
LIFELINE no
STANDARD HORIZON HX851: Yes
Some conclusions about the effectiveness of these two marine VHF radios:
• By manufacturers. Max Transmit Power, STANDARD HORIZON HX851 specifications are far superior to NAUTILUS LIFELINE DIVER.
• NAUTILUS Lifeline does not indicate its reception sensitivity specification in its user documentation, but many hours of lateral field testing showed that the STANDARD HORIZON HX851 can clearly receive VHF broadcasts that NAUTILUS LIFELINE DIVER cannot use.
• By manufacturers. STANDARD HORIZON HX851 has a significant additional voice range over LIFELINE.
• By manufacturers. the stated specifications, STANDARD HORIZON HX851 has a significant additional range of DSC message transmissions over LIFELINE.
• The HX851 STANDARD HORIZON antenna can be lifted 5 feet above water. The LIFELINE antenna cannot be extended longer than an arm's length, and the radio cannot be used for voice communication when it is held in the outstretched hand of a floating diver.
• The audio speaker in the STANDARD HORIZON HX851 has a much louder audio output than LIFELINES, which is very useful in windy conditions.
• STANDARD HORIZON HX851 will be FLOAT. DESIGNED Nautila.
Marine Division STANDARD HORIZON has more than 50 years. experience as a leader in the development of radio frequency VHF, the design of GPS receivers and the production of marine communication electronics. They are widely recognized as an industry leader that consistently produces best-in-class products.
There are a number of other features and functions of the STANDARD HORIZON HX851, which distinguish it further, as the best VHF radio control for a diver in an emergency. But I will leave it to the diver to compare these two radio stations further.
