The following FAQ details a number of questions we have received over the years regarding Hemisphere GNSS equipment as well as solutions to help you overcome your issue.
The FAQ is split into 3 main support sections and under the sections there are subheadings which detail a number of frequently asked questions and useful step by step guides for Hemisphere GNSS receiver users.
If you do not manage to solve your issue with your Hemisphere GNSS equipment, please contact your dealer and request assistance.
- Monitor the satellite signal levels in PocketMax4 throughout this processby going to the ‘Satellites’ tab. If the signal levels are poor then either look at moving to a location with better sky view or test the antennas
- Ensure you have a clear sky view
- Check the integrity of the antenna cables using a multimeter (For instructions on how to do this, please see 'How to test for continuity in antenna cables’ under the 'Antenna Based Problems’ subheading)
- Ensure you are well away from any nearby buildings or large objects, especially ones with metal surfaces which might be producing multi-path error.
- Confirm that the measured antenna separation on the receiver is the same distance as the actual antenna separation from centre to centre to the cm.
- Reduce the antenna baseline to 0.5m and adjust the measured antenna separation setting accordingly through either your receiver interface (Vector>Antenna Sep>Measured Antenna Separation>) or your receiver configuration software (e.g. Termite, PocketMax 4).
- Once lock is re-acquired, you can work on increasing your antenna separation to increase heading accuracy accordingly.
- If the GPS or SBAS lock is not re-acquired, please contact a member of your dealers technical support staff.
- Ensure antenna is at a different height to any equipment e.g RADAR that may be producing RFI.
- Try moving the antenna away from such objects that produce similar frequency waves to the bands that the antenna’s operate at or any equipment that has a high electro-magnetic output.
- Ensure your antenna has a clear sky view and is away from nearby buildings and large objects, especially ones with metal surfaces which might be producing multi-path error.
- Please follow this link to watch a YouTube video on how to test a co-axial antenna cable for continuity: https://www.youtube.com/watch?v=abIOq5zNS4k
This can be completed either through your receiver LCD display (see below for instructions), a serial terminal program or through PocketMax4.
- On your receivers display select the following:
- Depending on what activations are enabled on your receiver and which differential source you would like to use, cycle up or down the list and select the one you require.
- Alternatively, if you would like to exclude any diferential sources so your receiver doesn’t use them, follow the steps below (this will not disable any activations the receiver has)
- From there, you may configure what differential sources your receiver can use.
If you are not receiving Atlas corrections, this could be due to one of the following problems:
- Your receiver is not subscribed with an Atlas subscription. You can check this by sending your receiver the $JK,SHOW command via a serial terminal program and if your receiver replies with a date then this will be the expiry date of your Atlas subscription. If the date shows 00/00/2000 then your receiver does not have an Atlas subscription applied to it.
- Your antenna cannot see the Atlas satellite. As the Atlas satellites are in geostationary orbit on the Equator, depending on your location the Atlas satellite may be very low on the horizon. If your receiver is operating in the Northern Hemisphere then you will want to maintain a good view to the South and vice versa. As always, the higher you have your antenna, the better the signal reception will be and this will help reduce the chance of dropouts.
- You're in a high multipath environment. Like GPS, L-Band signal can be effected by Multi-path interference and as such it is worth keeping your receiver away from large metal surfaces.
- Your antenna is being scrambled by Inmarsat C. Atlas L-Band signal is suceptable to interference from Inmarsat C as it operates at similar frequencies. To remedy this, move the location of your antenna away from the Inmarsat C dome.
- Your receiver is not correctly configured to track the correct Atlas satellite in your region. You can check this by sending your receiver the $JFREQ command via a serial terminal program and it will respond with 2 frequency values e.g. $>JLBEAM,Sent 1545.905,Used 1545.905,Baud 600,Geo 25,AUTO. The ‘Sent’ value is the frequency to which the receiver is instructed to tune to and the ‘Used’ value is the frequnency to which the receiver is currently tuned to. The Baud should always be set to 600. To change the frequency, please see the $JFREQ command in the Hemisphere GNSS Technical refrence manual which is downloadable from their website (https://www.hemispheregnss.com/technical-documentation/)
- Your receiver is not powered sufficiently. Check that it’s receiving a stable/non-fluctuating voltage within the tolerance range mentioned on the product datasheet.
- The Atlas service is temporarily offline. Please check with your Atlas subscription provider.
- Please follow this URL link to identify your nearest Beacon transmitting station and to find out wether you are within its nominal range: http://www.gnsspro.com/referencestations.php
- Verify you are within a beacon reference stations area of coverage and close enough to receive corrections from the station.
- Ensure there are no sources of interference nearby e.g. large metal surfaces.
- Check your antenna connection.
- Verify the MSK rate is set correctly.
- Verify the frequency of transmitting beacon is set correctly.
- Select an alternate antenna position away from any possible sources of RF interference
- Once you know the transmitting frequency and baud rate of Beacon station you would like to tune your receiver to, follow the steps below that are entered through your receiver display:
- On the LCD display select:
- To confirm that the receiver is automatically tuning to the strongest beacon signal, select:
-Next to the frequency currently tuned in there should be the letters ‘AA’ which indicate that the receiver is in an automatically tuning beacon mode as opposed to ‘MM’ which indicates that the receiver is set for manually beacon frequency input.
- Power the receiver and connect to it with a PC terminal interface (Termite, Hyperterminal etc.)
- Test that you have bi-directional communications with the receiver. A way of doing this would be to send the $JI command and the receiver should respond.
- Copy and paste the whole activation code into the line entry and send the command to the receiver. The code will start with $JK,
- The receiver will come back with 'subscription accepted’, your receiver is now activated to receive the input subscription and you can now exit the terminal program. Wait 10 seconds, then power cycle the receiver
- If you received the response ‘Invalid code’, you have either incorrectly entered your subscription code or the code is invalid. Before contacting your dealer, please ensure you entered the subscription code exactly as written by your dealer. Please note that your subscription code will never contain the letter ‘O’ or letter ‘I’ due to being easily confused with the number ‘0’ or letter ‘l’. Any ‘0’ will be written as the number ‘0’ and not the letter ‘O’.
- If the subscription is still not accepted, contact your dealer.
- Boot up PocketMax 4 and connect your receiver to your computer
- Select the port tab that you wish to output the messages on
- Scroll down the list to the message which you would like to be output
- Near the bottom of the window there is a field which you can change from ‘Off’ to whichever output rate you wish the message to be set to (please note: 10Hz can only be output on receivers with 10Hz data output activated on their receivers, likewise with 20Hz and 50Hz)
- When you are done configuring, click the red exit button at the top right of PocketMax and make sure you ‘Save settings + disconnect’ for the changes to be made
If you would like to receive a quick start guide or troubleshooting guide for a specific Hemisphere GNSS product then please contact us and we will email you the relevant documentation.
Eden Business Park
Isle of Man
Tel.: +44 (0)1624 880366
Registered in the Isle of Man 120826C
VAT Reg. No. 003 1066 44