## 1 Introduction  
Path loss reduces the quality and strength of transmitted radio frequency (RF) energy along the propagation path from the transmitter to the receiver. This is primarily due to wave divergence and secondarily due to the interaction of the transmitted signal with the terrain, hydrometeors, and primary and secondary radio climatic factors on its propagation path [1, 2]. Investigation of the performance evaluation or error margins of empirical path loss models over wireless communication channels has become imperative for ensuring reliable power budgets and link design in any local environment. It is well known that existing empirical models do not fit perfectly in geographic environments or climates different from the original environments in which they were formulated [3; 4; 5; 6; 7; 8]. What is new, however, is how radio scientists and engineers have taken up the challenge to investigate the degree of reliability of these popular and standardized models in their geographic locations to enhance the quality of transmission and reception (QoTnR) of wireless signals. Based on the above, different researchers all over the world have carried out studies in this respect in their localities [7; 8; 9; 10; 11; 12]. Many authors have engaged in rigorous studies on path loss assessment and modeling and have evaluated the suitability of existing models for use in environments different from their original environments [6; 8; 13; 14; 15]. Related studies on path loss and coverage areas for AM and FM radio channels include the works of [16; 17; 18; 19]. Many studies have also been conducted on path loss assessment and have evaluated the performance of GSM signals both in Nigeria and internationally [9; 10; 11; 12; 15; 20; 21; 22]. Most of the findings of these studies have favored the use of one or two of the Okumura-Hata family models in their areas of study. Researchers have also captured studies on television channels in this regard. For analogue TV channels, the works of [3; 4; 5; 6; 7; 8; 23] are available. With the technology of digital terrestrial television (DTTV) gradually replacing analogue technology in Nigeria, few related studies have been reported on the digital UHF television channels in Nigeria, such as the works of [1; 24; 25; 26; 27]. Other scenarios where empirical path loss studies have been carried out include space-to-ground and rain-induced attenuation over the satellite-to-earth link system [28; 29]. There is still a need for many studies on path loss assessment and the evaluation of empirical models over DTTV channels in Nigeria. This will enhance proper coverage area assessments for existing digital terrestrial television stations and link design for full analogue switch-off (ASO) to digital switch over (DSO) in Nigeria. This forms the motivation and the gap this study aims to fill. The importance of empirical models in wireless communications are numerous, such as in path loss assessment, channel estimation, and coverage area prediction and mapping [3]. Empirical models are also useful for network optimization in communication and radio map systems [30], as well as in radio-link design and power budgeting over wireless channels [8; 27]. However, the study is not exhaustive and will continue to attract more findings aimed at achieving QoTnR due to the dynamic nature of terrain and weather in different geographic regions of the world. Over the years, the Okumura-Hata model and other improved versions based on it have been gaining acceptability over the VHF/UHF channels in some geographic locations [3; 9; 10; 14; 31]. Since accuracy and reliability are required, none of these models should be hand-picked for use in an environment without evaluating their performance to select the most suitable model. It was on this premise that we decided to investigate the reliability of four models belonging to the Okumura-Hata family. These include the Okumura-Hata, the European Cooperation for Scientific and Technical Research (COST-231), the European Communication Committee (ECC), and the Ericsson models.