| Q. |
Is the J30 pin to pin compatible with the J20? |
| A. |
Yes. However, if using push to fix modes, the Wake-up line (Pin 26) must be connected. In the J20 the Reset line was toggled to wake up the GPS in Push-to-Fix mode, but this functionality is now taken out to a separate input called the Wake-up pin. Customers must ensure that this line is toggled only after the GPS has in fact gone to sleep—if the GPS is still running when the RTC finite state machine is advanced, unexpected operation might occur. |
| Q. |
Can I use the same antenna for the J30 as for the J20? |
| A. |
The maximum input antenna gain for the J30 is lower than the maximum gain for the Jupiter 20. If you are using an antenna within the range of 18 to 26 dB gain (as stated by the manufacturer) with a cable of several metres attached, you should have no need to change the antenna. However, the J30 ideally requires LNA gain INPUT of 16 dB (max). So, if you are using an active antenna that does not have several metres of cable attached, you must ensure that the total gain exiting the antenna to the GPS is at a maximum of 18 dB. The areas of performance to monitor are Time-To-First-Fix in poor environments and the number and signal strength of satellites used in poor conditions. Please use our recommended antennas as a reference comparison for the performance of your antenna. Acceptable reference antennas include the Panasonic VIC-1 3 volt antenna and the Allis Antenna Corporation M820B antenna. |
| Q. |
Are the Jupiter 30 and Jupiter 20 interchangeable from a SW perspective? |
| A. |
In the standard ‘as shipped’ configurations yes. However, J30 does not support manual activation of the GPIO. For low power modes only Adaptive Trickle Power and Push to Fix can be activated. Standard Trickle power is not supported (Adaptive Trickle Power is automatically activated when Trickle Power is commanded). No DR option is currently available. |
| Q. |
What power saving should I achieve upgrading to the J30? |
| A. |
The average power saving in steady state is approximately 50 mA. Additional power savings of 50-90% (depending on your configuration) are possible using ATP and Push-To-Fix. Hot starts are achieved in less than one second, providing up to 93% energy saving. |
| Q. |
How should I configure my GPS receiver to perform optimally to my requirements? |
| A. |
Please contact your local Navman sales representative who will direct you to appropriate applications engineers to assist with your configuring and testing scenarios. |
| Q. |
Can I use the Jupiter 30 with a passive antenna and what type of antenna would Navman recommend? |
| A. |
Navman recommends an RCP passive patch antenna with a minimum gain of 0 dBi and ideally greater than 2 dBi. When choosing a patch antenna, the patch should not be smaller than 15 x 15 mm for good performance and should be on a minimum of 40 x 40 mm ground plane. Linear polarised antenna need 3 dB more gain to be equivalent to a 0 dBi RHCP antenna. The passive antenna must be no more than 10 cm from the GPS input for optimal performance, especially with very low gain passive elements. The antenna and input trace must be matched to the 50 ohm input impedance required. Poor RF return loss will result in significantly weaker performance. |
| Q. |
What are the battery back-up requirements? |
| A. |
Please ensure there is Vbatt voltage applied at ALL times to the battery back-up pin. This voltage must be between 1.9 and 3.6 volts under normal operation. If the voltage could drop below 1.8 volts at any time, please employ a voltage detector that cuts the voltage to the VBATT pin to 0 volts when this trigger voltage is reached. If there are special requirements for the Vbatt voltage please contact Navman for verification. |
| Q. |
Can I simply cut the power to the J30 to save power? |
| A. |
Yes, as long as you have Vbatt connected to a suitable noise free source. Power consumption should drop to 6uA being drawn for the Vbatt pin. On power up the device will perform a Hot or Warm start depending on how long it has been turned off. Time-To-First-Fix on power up is dependant on how often you turn the GPS back on and allow the ephemeris to be updated. |
| Q. |
Can I use the J30 in extreme temperatures? |
| A. |
Yes, we test the device from -40 degrees C to +85 degrees C. However the ramp in temperature must be kept to a minimum by insulating the GPS from rapidly varying sources of temperature. We qualify the J30 at a maximum of 2 degrees C per minute variation in temperature. Temperature ramps outside of this might have a negative effect on Time-To-First-Fix and Low power mode operation. |