Frequency Modulated Continuous Wave (FMCW) radar system has been developed and applied for various needs. Based on the conventional FMCW radar concept, a large bandwidth is needed to detect small displacements in the chest wall or abdomen related with respiratory activity. To overcome the need for large bandwidths in detecting vital respiratory signs, several improvements to the FMCW system are proposed in this paper. The phase-detection concept has been elaborated in improving the capability of FMCW to detect the small displacement. In developing multi-target detection capability, range detection capability through beat frequency output needs to be combined with the phase-detection method. Theoretical and simulation studies were performed to investigate the concept of combining range detection and phase detection for detecting respiration on multi-target. The results show that the proposed method is well-performed in detecting the multi-target respiration in high noise reflection.

ABSTRAK Pada pendeteksian pernafasan menggunakan sistem radar maka adanya pantulan dari sejumlah objek statis di sekitar target akan memberikan pengaruh pada hasil pendeteksian. Modifikasi pada sistem FMCW telah diusulkan untuk memberikan kemampuan dalam mendeteksi pernafasan multi target. Konsep deteksi fasa dilaborasi pada metode usulan untuk menghadirkan kemampuan deteksi pergeseran kecil. IQ demodulator jamak diusulkan sebagai konsep modifikasi pada sistem FMCW untuk permasalah tersebut. Pengujian kemampuan sistem usulan pada kondisi clutter dilakukan dengan melakukan kajian teoritis dan simulasi komputer. Pengujian dilakukan pada kawasan waktu dan kawasan frekuensi. Hasil-hasil yang diperoleh menunjukkan bahwa metode IQ demodulator jamak yang diusulkan memiliki kemampuan dalam mendeteksi pernafasan secara multi target dan mampu mempertahankan kemampuan tersebut pada kondisi adanya clutter. Kata kunci: deteksi pernafasan, multi target, FMCW, IQ demodulator, clutter ABSTRACT In the detection of respiration using a radar system, the reflection of static objects around the target will have an effect to the detection results. Modifications to the FMCW system have been proposed to provide the ability to detect multi-target respiration. The concept of phase detection is elaborated on the proposed method to provide small shift detection capabilities. Multiple IQ demodulator is proposed as a modified concept on the FMCW system for this problem. Testing the ability of the proposed system under clutter conditions is carried out by conducting theoretical studies and computer simulations. Tests carried out in the time zone and frequency region. The results obtained indicate that the proposed multiple-method IQ demodulator has the ability to detect multi-target respiration and is able to maintain that ability in the presence of clutter. Keywords: respiration detection, multi target, FMCW, IQ demodulator, clutter