Paul Voglewede

Asynchronous dynamic network discovery for low power systems

Unattended ground sensor systems (UGS) have become an important part of a covert monitoring arsenal in operations throughout the world. With the increased use of unattended ground sensor systems, there is a need to develop communication architectures that allow the systems to have simple emplacement procedures, have a long mission life, and be difficult to detect. Current ad-hoc networking schemes use either a network beacon, extensive preambles, or guaranteed time synchronization to achieve reliable communications. When used in wireless sensor systems many of these schemes waste power through unnecessary transmissions. These schemes compromise the covert nature of UGS through excess transmissions for a non-beaconed network or the periodic beaconing in a beaconed network. These factors are detrimental to sensor systems, which chiefly rely on being covert and low-power. This paper discusses a nonarbitrated, non-GPS synchronized, beaconless approach to discovering, joining, and reliably transmitting and receiving in a low-power ad-hoc wireless sensor network. This solution is capable of performing network discovery upon demand to get an initial alignment with other nodes in the network. Once aligned, end points maintain alignment and can predict when other nodes will be available to listen.

Frequency hopping with multih CPM (MIL-STD-188-181B)

Multi-h CPM waveforms have been primarily used in satellite communications (MIL-STD-188-181B). In recent years, multih CPM has been getting more attention for use in a line of site (LOS) mode of operation. To improve the effectiveness of multi-h CPM waveforms in LOS, frequency hopping can be added to provide electronic counter-countermeasure capability for hostile environments and frequency diversity to combat multipath. This paper discusses some of the design aspects and a possible solution for a coherent frequency hopping multi-h CPM waveform that does not use pilot symbols. The performance of the hopping CPM 16k bps is expected to be approximately 6 dB better than fixed frequency 16 k FSK. The price for the improved capability is approximately twice the loading of existing multih CPM demodulation with a signal bandwidth of 35 kHz.

Unattended ground sensor system architecture for reduced information dissemination timeline

In a multi-layered command structure, information from unattended ground sensor systems has typically been transferred from the observation area to the highest level of command. The information is analyzed from many such regions and disseminated to the appropriate forward operating base as intelligence or action orders. Some missions, like the detection and interdiction of Time Critical Targets, may be hampered by the current data dissemination timeline. Therefore alternate, faster methods of providing actionable intelligence into theater are required for these missions. This paper discusses alternative architectures that reduce the information dissemination time line from the sensor fields through the command center and back down to the quick reactionary forces.

Efficient error free data transmission in a line of sight bandlimited channel

The creation of reliable IP networks in a mobile tactical wireless environment requires efficient channel access and reliable RF data transmission. This paper shows how an automatic repeat request system with adaptive waveform selection can greatly increase the channel throughput over frequency shift keying with adaptive forward error correction. The difference can be as much as 4 times the throughput rate of current systems.

Adaptive filter method for deriving digital IF filters

For many modulation schemes it can be difficult to derive an IF filter which is best suited for all symbols. In particular, any tailoring of the symbol shaping, additional receiver out of band rejection, or difficult analytical solutions can lead to digital IF filters that produce suboptimal performance. For these instances, an alternative solution for IF filter design methodology is proposed. Digital IF filters can be created in simulation using common adaptive filtering techniques. In a single step, the tap values for a digital IF filter with specified adjacent channel rejection can be generated. This paper verifies the adaptive filter method for deriving digital IF filters using a non-constant envelope 8-ary phase shift keying modulation and a constant envelope 8-ary continuous phase modulated waveform.