Design and production of embedded electronics, software, telemetry- and remote-control applications


GPRS transfer system for intermediate timing

The new intermediate timing system for orienteering is a system primarily made for use with standard Emit controls and will add a fast and simple transfer of intermediate timing directly into the eTiming database.

Functional overview of the NovOtime system. Click on the image for more detailed view

The Emit control units can be connected either by RS232 cable if the unit is an online module or it can be equipped with a small pickup antenna fitted underneath an ordinary Emit control. In either case, the punching will be captured an forwarded to a central server with minimum delay, tagged with an event time from a server synchronized clock that will give a an intermediate time accurate to within 100-200ms. All data will be buffered and retransmitted until received by the server.

The server will reformat and store the short punch-messages received from the modules and save them to disc on XML-format. Data can be retrieved from the server at any time, either manually or automatically by a PC application. The server will have a backup server placed at a geographically distant location to give optimal safety against local infrastructure problems. This can be essential for use with critical applications such as major sports events.

The Java based PC application is run locally on a PC connected to the network at the event centre. It automatically download all punches instantly as they arrive on the server and import the data directly into the intermediate database part of eTiming. Data will also be saved to local disk on XML format and can be reformatted and exported by a custom part of the application program. In this way, data may be exported into almost any other kind of result database or result presentation system.

NovOsense pickup antenna

As an alternative to using standard Emit controls with RS232 cable output, Novatron has developed a simpler NovOsense pickup antenna that fits nicely under any standard Emit control. The antenna unit is waterproof and is less than 2mm thick so that it can be easily fitted underneath the Emit control. Just loosen the screws to give an opening of 2 mm underneath, slide the antenna in place and tighten up again. It can't be simpler.

NovOtime GPRS module

The units are 50mm wide, 25mm thick and has a length of 180mm. With the standard whip antenna fitteed, the total length will be approx. 300mm. The total weight of GPRS module with internal battery pack and whip antenna is approx. 350g. The weight of a NovOsense pickup antenna/receiver with 2m cable is approx. 120g.


The NovOtime module is weatherproof and can withstand direct rain without additional protection

Operating temperature is limited by the LiIon battery pack to : -20 - +60°C, even though the electronics itself can handle a wider temperature range.

The module is equipped with a TNC for the whip antenna which means that the whip can easily be exchanged with a larger omni directional antenna or a directional antenna connected by cable if necessary.

Connection to the controls or NovOsense pickup antenna goes through a 9 pin DSUB connector in the bottom. Connecting the plug also act as an on/off-switch so that the unit automatically starts when the connector is attached. After attaching the plug, the module will connect to the server and download configuration data. Depending on the setup, the module will either go into sleep, stay idle on-line or go into active run mode. Removing the plug will put the module into shutdown-mode and finally back into power off mode.

The unit has 4 input lines so that it might connect to 4 pickup antennas, 4 Emit online controls with cable or a combination of these.

The system uses 2 SIM cards so that the system may have 2 alternative networks to connect to for optimal operation. This prevents the module from failing if one network is overloaded or suffer other problems that reduce or stop traffic.

It is possible to connect 2 GPRS devices to the same pickup antenna, thus enabling simultaneous transmission of all data on 2 separate networks. This will in addition to redundancy also reduce problems with intermittent traffic peaks that can increase transfer delays. As it is unlikely that the traffic peaks will occur at exactly the same time in both networks, a duplicated solution will give a lower and more stable transfer delay.

The modules use Li-Ion battery packs with a capacity of 4.4Ah, something that will be sufficient for runs spanning several days or long overnight relays such as Jukola or 10-mila. The current battery voltage and capacity is monitored constantly and transferred to the server at regular intervals for presentation on the module status part of the PC-application. External power may be connected at any time during operation in case status from the modules indicates that the battery voltage or battery capacity is reaching an unsatisfactory low value.

The batteries are charged from special chargers supplied with the units

Transfer speed

Transfer of data to server will take from 200ms and up depending on the traffic load in the network. The capacity is large enough to handle simultaneous punching at a rate of 1Hz on all 4 channels. This is more than enough for handling the worst case scenario in relays. In cases where the control can be viewed by spectators and a delay will be clearly visible, a special mode with better control over network allocation may be used, but at the cost of a significantly larger power consumption. External power supply is recommended in this case. On critical controls, the use of two modules connected to different networks should be considered to increase safety and reduce peak delays even more.

PC-application

All system setup is done through the graphical user interface on the PC. The idea behind the design is that the system should be available to any operator with a minimum of training and could be handled by the club's computer personnel without the need for external support. As the system is configured through the server, it is also possible for experts form Novatron to assist remotely with the configuration if necessary.

Normally, the operator has to configure the control codes in the application. With the NovOsense pickup antenna, this information may be acquired automatically from the control unit, thus making control code configuration unnecessary.

The visible part of the application is small and consists of a narrow windows with a number of buttons. Additional windows for configuring server details and control parameters may be opened when needed. The same applies to status windows providing traffic and status data during a run.

For supervision, it is possible to open a larger window that provides traffic intensity and delay information on a sliding timescale. The position of the bars indicates the time of the punching event, while the height and colour indicates the delay experienced from the event was triggered until it is received by the PC-application. Scanning through this graph on all modules provides a good overview of the current traffic situation

The module status window provides information about battery voltage and remaining battery capacity, GSM signal level, serial no. and control no. In addition, statistical data about the module to server transfer times is provided. Critical values as battery voltage, charge and signal strength will be colour coded and changes to orange and finally red when values are getting close to limits.

The buttons on the main toolbar can be set to flash on every punch so that the person controlling the result service can have a visual indication of activity without having to bring up the larger traffic window. It will also be able to enable an audible punch warning that can be selected individually for each control. This feature will typically be used for attracting action when the first runners start punching on a new control. In this way, there is no need to keep an eye on the screen all the time.


Screen dump from PC shows the small main window in the upper right. This is the part that will always be visible (on top of other applications). Below follows a window with status information about the selected module and finally at the bottom, the GPRS traffic data window. Green represents transfer times below 0.5s, yellow is between 0.5 and 1s, magent is between 1 og 2s and red above 2s. Also notice the weak grey markers at regular 1 minute intervals that are communication test messages used to monitor module and GPRS-connection in cases with little or no traffic.

Experiences

The results from use at events like Norwegian Spring and O-festivalen indicates that the pickup antenna works fine and provides intermediate timing with no loss of data.

The major advantage is however its small size low weight and ease of installation. A runner with a small backpack can easily carry out and install 10 units along the course within an hour or two.

It doesn't have to be planned in advance. As there is no need for special controls or special control codes, a control already deployed in the forest may be equipped with the intermediate timing equipment in just a few minutes.

The modules have a "setup assist" mode that show signal status and test the control interface even before the system goes on-line. This provides a fast and simple feedback to the person deploying the modules.

HKK/14.09.2012